Avaya ATM Half-Bridge User Manual

BayRS Version 14.00 Part No. 308611-14.00 Rev 00

September 1999 4401 Great America Parkway

Santa Clara, CA 95054

Configuring ATM Half-Bridge Services

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308611-14.00 Rev 00

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308611-14.00 Rev 00

iii

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Preface

Before You Begin .............................................................................................................xiii

Text Conventions .............................................................................................................xiv

Acronyms ........................... .......................... .......................... ......................... .................xvi

Hard-Copy Technical Manuals . ....... ...... ....... ............................................. ...... ....... ........xviii

How to Get Help ............................................................................................................xviii

Chapter 1 ATM Half-Bridge Overview

What Is ATM Half Bridge? ..............................................................................................1-1

How the AHB Router Works ...........................................................................................1-4

Forwarding Inbound Packets from CPE Hosts .........................................................1-4

Forwarding Outbound Packets to CPE Hosts ..........................................................1-5

Using DHCP to Dynamically Assign IP Addresses ..................................................1-5

Dynamically Learning New Bridge Table Entries .....................................................1-7

Unsecure Learning Method ...............................................................................1-8

Secure Learning Method ...................................................................................1-8

Maintaining the AHB Bridge Table ...........................................................................1-9

Adding Bridge Table Entries ..............................................................................1-9

Removing Bridge Table Entries .......................................................................1-10

Replacing Bridge Table Entr ies ....... ...... ....... ...... ....... .......................................1-10

Using Source-Based Routing .................................................................................1-10

Responding to Proxy ARP Requests .....................................................................1-11

Using Inbound Packet Filtering ..............................................................................1-12

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Chapter 2 Starting AHB Services

Network Planning Considerations ..................................................................................2-1

AHB Configuration Requirements ..................................................................................2-1

Preparing a Configuration File .................................................................................2-2

Configuring an IP Interface on the Router ................................................................2-3

Configuring Circuitless IP on the Router ..................................................................2-4

Configuring AHB Services ..............................................................................................2-5

Creating an ATM Interface ........................................................................................2-6

Adding an LLC/SNAP PVC Service Record ............................................................2-6

Adding AHB to the LLC/SNAP Service Record .......................................................2-7

Adding PVCs to the LLC/SNAP PVC Service Record .............................................2-9

Configuring a DHCP/BootP Relay Agent ......................................................................2-10

Creating a BootP Relay Agent Forwarding Interfaces ............................................2-10

Configuring BootP Preferred Servers .....................................................................2-12

Specifying the Relay Agent IP Address ...........................................................2-12

Specifying the Target Server IP Address .........................................................2-13

Chapter 3 Customizing AHB Services

Modifying the AHB Configuration ...................................................................................3-1

Enabling and Disabling AHB ....................................................................................3-1

Setting the Auto Learn Method ................................................................................3-2

Configuring a Local AHB Init File .............................................................................3-3

Sample Init File ..................................................................................................3-3

Specifying an Alternate Init File ...............................................................................3-5

Specifying the Debug Level ......................................................................................3-6

Enabling and Disabling Inbound Packet Filtering .....................................................3-7

Modifying AHB Circuits ...................................................................................................3-8

Enabling and Disabling an AHB Circuit ....................................................................3-8

Specifying the Subnet Mask for the Learned Host ...................................................3-9

Enabling and Disabling Proxy ARP on a Circuit .....................................................3-10

Configuring Traffic Filters for Source-Based Routing ....................................................3-10

Deleting AHB from the Router ......................................................................................3-11

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Appendix A AHB, BootP/DHCP, IP, and ATM Parameter Descriptions

AHB Global Parameters ................................................................................................ A-2

AHB Circuit Parameters ................................................................................................. A-6

BootP Relay Agent Interface Table Parameters ............................................................. A-8

BootP Address Parameters ......................................................................................... A-10

BootP Relay Agent Preferred Server Table Parameters .............................................. A-12

BootP Preferred Server Configuration Parameters ...................................................... A-14

IP Configuration Parameters .................................... ............................................. ...... A-15

ATM Interface Parameter Descriptions ..................... ...... ....... ...... ................................ A-17

ATM Service Record Parameter Descriptions ............................................................. A-19

ATM Virtual Channel Link Parameter Descriptions ...................................................... A-23

Appendix B Understanding ATM Concepts

ATM General Information ............................................................................................... B-1

ATM Cells ................................................................................................................ B-1

Cell Headers ..................................................................................................... B-1

ATM Data Transmission ........................................................................................... B-3

Permanent Virtual Connections .............................................................................. B-5

Service Records and Virtual Circuits ............................................................................. B-5

Data Encapsulation ....................................................................................................... B-5

Assigning a Data Encapsulation Type for a PVC .................................................... B-6

PVC Access Methods .................................................................................................... B-6

Multiple PVCs .......................................................................................................... B-7

One PVC ................................................................................................................. B-8

Index

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Figures

Figure 1-1. DSL Network with an AHB Router ...........................................................1-3

Figure 1-2. How CPE Hosts Identify a DCHP Server .................................................1-6

Figure 1-3. How CPE Hosts Request and Receive IP Addresses from

the DHCP Server .....................................................................................1-7

Figure A-1. Edit ATM Half-Bridge Global Parameters Window .................................. A-2

Figure A-2. ATM Half-Bridge Circuit List .................................................................... A-6

Figure A-3. BOOTP Relay Agent Interface Table Window ......................................... A-8

Figure A-4. BOOTP Addresses Window .................................................................. A-10

Figure A-5. BOOTP Relay Agent Preferred Server Table Window .......................... A-12

Figure A-6. BOOTP Preferred Server Configuration Window .................................. A-14

Figure A-7. Interface Attributes Window Sequence ................................................. A-17

Figure A-8. Service Attributes Window Sequence (PVCs) ...................................... A-20

Figure B-1. ATM Cell .................................................................................................. B-2

Figure B-2. ATM Transmission Components .............................................................. B-4

Figure B-3. Multiple PVCs per Service Record ......................................................... B-7

Figure B-4. One PVC per Service Record ................................................................. B-9

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Tables

Table 1-1. Sample AHB Bridge Table .......................................................................1-9

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This guide describes asynchronous transfer mode (ATM) Half-Bridge services and what you do to start and customize ATM Half-Bridge se rvices on a Nortel Networks

™

Before You Begi n

Before using this guide, you must complete the following procedures. For a new router:

• Install the router (see the installation guide that came with your router).

Preface

router.

• Connect the router to the network and create a pilot configuration file (see

Make sure that you are runni ng the lates t versio n of Nortel Netw orks BayRS Site Manager software. For information about upgrading BayRS and Site Manager, see the upgrading guide for your version of BayRS.

308611-14.00 Rev 00

Quick-Starti ng Router s , Conf igur ing BaySt ac k Remote Acc ess , or Connecting ASN Routers to a Network).

™

and

xiii

Configuring ATM Half-Bridge Services

Text Con ventions

This guide uses the following text conventions:

bold text

Indicates command names and options and text that you need to enter.

Example: Enter Example: Use the

show ip {alerts | routes

dinfo

command.

italic text Indicates file and directory names, new terms, book

titles, and variables in command syntax descriptions. Where a variable is two or mor e words, the words are connected by an underscore.

Example: If the command syntax is:

show at

valid_route

is one variable and you substitute one value

for it.

screen text Indicates system output, for example, prompts and

system messages. Example:

Set Trap Monitor Filters

separator ( > ) Shows menu paths.

Example: Protocols > I P ide nti fies the IP option on the Protocols menu.

xiv

vertical line (

) Separates choices for command keywords and

arguments. Enter only one of the choices. Do not type the vertical line when enteri ng the command.

Example: If the command syntax is:

show ip {alerts | routes show ip alerts

}

, you enter either:

show ip routes

, but not both.

308611-14.00 Rev 00

Acronyms

Preface

This manual uses the follow i ng acr onyms:

AAL ATM adaptation layer ADSL asymmetric digital subscriber line AHB ATM Half Bridge ARE ATM Routing Engine ARP Address Resolution Protocol ATM Asynchronous Transfer Mode ATU-C ADSL terminal unit, central ATU-R ADSL terminal unit, remote AUI Attachment Unit Interface BootP Bootstrap Protocol BRI Basic Rate Interface CO central office CCITT International Telegraph and Telephone Consultative

DHCP Dynamic Host Configuration Protocol DSL Digital Subscriber Line CPE customer premise equipment DSLAM DSL access multiplexer DTE data terminal equipment GUI graphical user interface HDLC high-level data li nk control ILI Intelligent Link Interface IP Internet P rotocol ISDN Integrated S ervices Digital Network ISO International Organizat ion for Stand ardization ISP internet service provider

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Committee (now ITU-T)

Configuring ATM Half-Bridge Services

ITU-T International Telecommunications

LAN local area network MAC media access control MAU media access unit MIB management information base MTU Maximum Transmis sion Unit OSI Open Systems Interconnection PDU protocol data unit PVC permanent virtual circuit RIP Routing Information Protocol SAP service access point SDU service data unit SNAP Subnetwork Access Protocol STAT status

Union-Telecommunications (formerly CCITT)

xvi

SVC switched virtual circuit TCP/IP Transmission Control Protocol/Internet Protocol UTP unshielded twisted-pair VC virtual circuit VCI virtual connection id entifier VCL virtual channel link VPI virtual path identifier WAN wide area network

308611-14.00 Rev 00

Hard-Copy Technical Manuals

You can print selected technical manuals and release notes free, directly from the Internet. Go to support.baynetworks.com/library/tpubs/. Find the product for which you need documentation. Then locate the specific category and model or version for your hardw are or soft ware product . Usi ng Adobe Ac robat Re ader, you can open the manuals and releas e notes, search for the sections you ne ed, and print them on most standard printers. You can download Acrobat Reader free from the Adobe Systems Web site, www.adobe.com.

You can purchase selected documentation sets, CDs, and technical publications through the collateral catalog. The catalog is located on the World Wide Web at

support.baynetworks.com/catalog.html and is divided into sections arranged

alphabetically:

• The “CD ROMs” section lists available CDs.

• The “Guides/Books” section lists books on technical topics.

• The “Technical Manuals” section lists available printed documentation sets.

Preface

How to Get Help

If you purchased a service contract for your Nortel Networks product from a distributor or authorized reseller, contact the technical support staff for that distributor or reseller for assistance.

If you purchased a Nort el Net wor ks s ervice pr ogram, c ontact one of the f ollowing Nortel Networks Technical Solutions Centers:

Technical Solutions Center Telephone Number

Billerica, MA 800-2LANWAN (800-252-6926) Santa Clara, CA 800-2LANWAN (800-252-6926) Valbonne, France 33-4-92-96-69-68 Sydney, Australia 61-2-9927-8800 Tokyo, Japan 81-3-5402-7041

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xvii

Chapter 1

ATM Half-Bridge Overview

This chapter provides an overview of basic ATM Half-Bridge concepts and the specific ways Nortel Networks implements these concepts on BLN routers.

This chapter assumes that you understand ATM concepts and terminology. For a brief overview of ATM, see Appendix B. For detailed information about ATM, refer to Configuring ATM Services.

and BCN®

This chapter contains information about the following topics:

Topic Page

What Is ATM Half Bridge? 1-1 How the AHB Router Works 1-4

What Is ATM Half Bridge?

ATM Half Bridge (AHB) is a protocol operating on BLN and BCN routers that connect remote hosts ( PCs and w orks tati ons) at tached to an IP route d net work vi a digital subscrib er line (DSL) devices (modems). The modems send and receiv e I P packets over ATM PVCs using RFC 1483 SNAP/LLC encapsulation. AHB converts RFC 1483 bridge frames containing IP packets to unencapsulated routed frames and performs the reverse function for packets returning from the opposite direction.

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1-1

Configuring ATM Half-Bridge Services

Nortel Networks designed AHB to meet the requirements of public network providers who want to develop an end-to-end solution using DSL to provide high-speed internet an d remot e LAN acce ss t o ISP’s and corporate networks. The AHB router supports the public network provider’s WAN infrastructure network by performing the bi dire ction al conversion of RFC 1483 Ethernet bridge d pack ets for IP routing to and from the ISP and corporate networks.

Figure 1-1

shows a sample DSL access network that uses an AHB router. This

network is divided into four separate segments:

• The customer premises, which consist of th e remote host and modem, referred to as ADSL terminal unit, remote end devices (ATU-R)

• The network provider POP, which consists of DSL access multiplexor ADSL terminal unit, central devices (DSLAM ATU-C), ATM access network, and the AHB router

• The public network WAN infrastructure (typically IP over ATM or frame relay)

• The ISP or corporate network, which provides internet service for remote CPE stations

1-2

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0050

ATM Half-Bridge Overview

Remote

customer premises

802.3

PC1

PC2

802.3 AAL ATM

ATU-R

ATM over DSL

Network provider

central office

DSLAM

ATU-C

M U X

DSLAM

1483 encapsulated IP

packets in ATM

802.3 AAL ATM

OC-3 link

BLN/BCN

router

Frames

Figure 1-1. DSL Network with an AHB (BLN/BCN) Router

WAN

infrastructure

ATM

Frame relay

ISP or

corporate network

ISP1

Corp1

Corp2

ISP2

ATM

The following steps explain how IP packets travel from th e CPE host (remote user) on an Ethernet segment to the AHB router located at the public network provider’s central office:

308611-14.00 Rev 00

A user (PC or workstation) at a remote site sends Ethernet packets to an ATU-R attached to a remote Ethernet LAN segment (10 MB).

The ATU-R, acting as an Ethernet/ATM bridge, performs the following tasks:

• Accepts the Ethernet packets

• Segments the Ethernet packets into ATM cells according to RFC 1483

(802.2/LLC bridge encapsulation)

• Transmits the ATM cells to a DSLAM ATU-C at the public network

provider’s site

The ATU-C receives the ATM cells, which are multiplexed along with cells from other ATU-Cs, and tra nsmits them t o the ATM netw ork o v er one or more OC-3 links.

1-3

Configuring ATM Half-Bridge Services

The ATM network, located at the central office, switches the ATM cells and forwards them over PVCs to the ATM interface on the AHB (BLN/BCN) router.

How the AHB Router W orks

AHB combines bridging and I P routin g on the r outer pla tform. On t he DSL access side, the router receives RFC 1483 encapsulated bridged Ethernet frames containing IP packets from CPE hosts. On the WAN side, ISP’s and corporate networks receive routed IP frames. AHB dynamically learns the association between IP addresses assigned to CPE hosts and the correct RFC 1483 bridged Ethernet header data for the host.

Forwarding Inbound Packets from CPE Hosts

AHB decapsulates and then routes IP packets it receives from a remote CPE host to an ISP or corporate network. When AHB receives the incoming packets on its ATM inte rface, it checks its local b ridge table to determine whether the p acket’s source IP address corresponds to the host IP address in the associated AHB table entry. If the bridge table contains the bridge entry, and the entry matches the bridge information (the correct circuit and VCID), then AHB strips off the RFC 1483 bridged Ethernet header information and forwards the packet using IP routing to the appropriate ISP’s and corporate networks.

1-4

If AHB does not find the bridge entry in its local bridge table, and you selected unsecure learning mode, AHB creates a new bridge entry using the packet header data from the incoming packet. If you selected secure learning mode, AHB creates a new bridge entry only if this is a new DHCP request (for information about using unsecure and secure learning mode, see “Dynamically Learning New

Bridge Table Entries”). The AHB router cannot use this bridge entry until it

receiv es a DHCP reply on a non-AHB interf ace that matches the desti nation MAC address in the bridge ent ry. The IP address is assig ned at this time. If no matching bridge entry is found for an i ncoming pack et on an AHB interf ace, the pack et may still be forwarded if either it is a DHCP packet or if you have disabled inbound packet filtering.

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Forwarding Outbound Packets to CPE Hosts

IP packets received from ISPs or corporate networks that are destined for CPE hosts are sent to AHB b ased on th e AHB rout e in t he IP r outin g tabl e. When AHB receiv es I P pack et s, it sea rches its loc al bridge t able fo r an asso cia ted bri dge ent ry based on the packet’s destination IP address. If AHB finds an associated bridge entry, it adds the RFC 1483 encapsulation and Ethernet header information to the packet. Then it forwards the packet on the correct outgoing interface and PVC to reach the remote CPE host.

If AHB does not f ind a n associ ated bri dge entr y for the pack et in its br idge ta ble, it drops the packet.

Using DHCP to Dynamically Assign IP Addresses

CPE hosts can use DHCP to obtain their IP address and default gateway address. When you boot the router, the CPE host sends a DHCP request packet, which is relayed by the DSL modem to the AHB router. The AHB router acts as a DHCP/ BootP relay agent. When the BootP relay agent configured on the ATM service record receives the DHCP request packet, it fills in the associated IP interface address (the address you specified for the ATM interface) as the gateway address. The BootP relay agent then forwards the packet to the DHCP server using either the BootP forwarding interface method or the BootP preferred server method.

ATM Half-Bridge Overview

When the DHCP server receives the DHCP REQUEST packet, it checks to see whether the gateway address is filled in. If this address is fille d in, DHCP sends a reply packet (DHCPACK) to the BootP relay agent on the AHB router. The AHB router then forw ar ds t he DHCPACK reply to the CPE ho st usi ng th e a sso ciated IP address of the unnumbered IP interface.

DHCP servers often use the gateway address in the DHCP request to determine the address pool to use when assigning a client IP address.

The DHCP server may not respond if it receives a DHCP request where the gateway address is on the same subnet as the DHCP server’s IP address. Therefore, when selecting an associated IP address for the unnumbered ATM circuit, choose an add re ss other than the IP a ddr ess of a di re ctl y conn ect ed DHCP server.

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1-5

Configuring ATM Half-Bridge Services

Figure 1-2 shows how the remote hosts identify the DHCP server on the network.

Remote

host

1. Remote host broadcasts a DHCPDISCOVER

PC1

PC2

ATM

packet.

4. BootP relay agent forwards DHCPOFFER message to CPE host.

AHB router (BootP relay agent)

DHCP server

Figure 1-2. How CPE Hosts Identify a DCHP Server

2. BootP relay agent transmits DHCPDISCOVER packet to DHCP server that supplied a DHCPOFFER packet.

3. DHCP server transmits DHCPOFFER message to BootP relay agent in AHB router.

ISP1

Corp1

Corp2

ISP2

ATM0053A

1-6

Figure 1-3 shows how the CPE hosts request and receive IP addresses from the

DHCP server.

308611-14.00 Rev 00

ATM Half-Bridge Overview

Remote

host

PC1

PC2

ATM

1. Remote host broadcasts DHCPREQUEST packet.

4. BootP relay agent agent transmits DHCPACK packet or DHCPNAK packet to remote host.

AHB router (BootP relay agent)

DHCP server

2. BootP relay agent forwards DHCPREQUEST packet to DHCP server using the preferred server or forwarding interface method.

3. Target DHCP server transmits DHCPACK packet or DHCPNAK packet to BootP relay agent.

ISP1

Corp1

Corp2

ISP2

ATM0054A

Figure 1-3. How CPE Hosts Request and Receive IP Addresses from the DHCP Server

Dynamically Learning New Bridge Table Entries

The AHB router dynamically learns new bridge entries it receives from CPE hosts. You can determine the method by which AHB learns these entries by configuring the auto learning method configuration parameters on the AHB router. AHB provides the following auto learning methods:

• Unsecure

•Secure

• Both (default)

•None

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1-7

Configuring ATM Half-Bridge Services

Unsecure Learning Method

AHB learns new bridge entries from any IP and ARP packets it receives on ATM/AHB-configured inter faces when you set the auto learn method to unsec ure or both.

Secure Learning Method

When you set the auto learning met hod to Secure or Both, AHB learns ne w bridge entries from DHCP replies sent on AHB-configured circuits. Secure entries take precedence over unsecure entries.

Before you can use secure learning mode, make sure that you:

• Configure BootP on both the unnumbered ATM interface and on the associated numbered IP interface.

• Configure a BootP preferred server or forwarding interface on the unnumbered ATM interface (use the circuit number as the IP source address).

• V e rify that the IP ad dress assigne d by the DHCP serv er is on a dif ferent subnet than the BootP gateway address (that is, the associated numbered IP interface).

1-8

In secure learning mode, the AHB router serves as a BootP relay agent, forwarding DHCP requests it receives from CPE hosts.

When you set the learning method to both, AHB learns bridge entries either securely and unsecurely. When you set the learning method to None, AHB will not learn new bridge entries.

For information about configuring the auto learn method on an AHB router, see “Setting the Auto Learn Method”on page 3-2.

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Maintaining the AHB Bridge Table

AHB maintains a bridge t able o n each s lot. The tabl e cont ains a lis t of h ost en tries to or from which the router will forward traffic. These host entries map the IP address of a CPE host to the following:

• ATM interface on which it is learned on the AHB router

• Virtual Path Identi fier /Virtual Channel Ident ifie r (VPI/VCI) number

• RFC 1483 encapsulation type

• Ethe rnet header information

ATM Half-Bridge Overview

Table 1-1

Table 1-1. Sample AHB Bridge Table

Host ID

200.10.10.1 2 101/31 Bridged Ethernet frame:

shows a sample AHB bridge table.

Outgoing Circuit VPI/VCI RFC 1483 Bridge Header

src MAC addr= 010203040506 dest MAC adrr= 07080oaaboc Ethertype= 0800 (IP)

Adding Bridge Table Entries

In unsecure learning mode, AHB adds a new entry to the bridge table whenever it receives an IP or ARP packet that is not already in the table.

In secure learning mode, AHB adds new entries to its table when it receives certain incoming and outgoing DHCP messages. AHB adds new table entries when the CPE host on the remote site s ends a DHCPDI SCOVER message (source IP address equals 0.0.0.0). This new table entry identifies the incoming port, VPI/VCI, and RFC 1483 encapsulation data (including source MAC address). There is no IP address fo r the new table entry at this point.

AHB forwards only certain DHCP packets (ACK or NAK) to the CPE host using this entry before an IP address is assigned. When AHB receives a DHCPACK message, it updates the table entry to id entify the cor rect IP addr ess as provi ded by the DHCP server. When AHB learns the first host entry on a network, it inserts a route into the IP routing table for that network.

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1-9

Configuring ATM Half-Bridge Services

Removing Bridge Table Entries

AHB removes an existing table entry whenever it adds a new entry with the same source MA C a ddress , ATM port, and VPI/VCI n umber. AHB also removes a ta ble entry when it receives a DHCPRELEASE message (assuming that the source IP address-to-ATM port /VPI /VCI ma ppi ng is correct). If the entry b ein g re moved is on the original sl ot , al l other slots that h ave received copies ar e notified t o r emove those entries. When AHB removes the last host entry on a network, it deletes the corresponding route from the IP routing table.

Replacing Bridge Table Entries

If the bridge table contains a bridge entry that was learned on a different circuit/ PVC, and AHB learns another IP packet with the same IP address on a different circuit and VCID, then AHB replaces the old entry with the new entry. New entries that AHB learns in unsecure mode do not replace existing entries learned in secure mode, even if AHB learned them on different slots.

Using Source-Based Routing

The network provider can use source-based routing to ensure that the packet sent from a CPE ho st travels to the correct ISP gateway first, regardless o f its destination address. The ISP gateway can be an edge router directly connected to an AHB router via a WAN interface (frame relay, PPP) or a router located within the ISP’s domain. This option allows multiple links connecting the AHB router with the ISP network. If one link or edge router fails, traffic from ATM-attached hosts is routed via another edge router.

1-10

You use source-based routing by configuring an IP traffic filter on the ATM interface. You must specify traffi c filter criteria and a traffic filter action. The traffic filter criteria is the range of source IP add resses allocated to CPE hosts belonging to a single ISP. You must configure a separate traffic filter for each range of source addresses that get assigned to the ATM-attached hosts by an ISP. These filters must be installed on every AHB circuit.

The traffic filter action is “forward to next hop,” wh ich identifies the ISP’s gateway device. The next-hop address in the traffi c filter need not be a directly attached host. If it is not a directly attached host, AHB accesses the routing table to determine the directly attached host to which the packets are sent.

308611-14.00 Rev 00

You can use the “forward to next hop” feature to improve reliability. Consider an example where an ISP home network has two border routers: 200.1.2.3 and

200.3.4.5. If the source-based routing gateway address (next-hop address in the

traffic filter) is advertised by both border routers, t hen the AHB ro uter will send packets from the ATM-attached hosts to whichever border router has the best route. If this border router fails or if the link goes down, then the packets are sent to the alternate border router. The gateway address does not need to belong to a real device because the ISP border router forwards packets based on the destination IP address.

For information about configuring IP filters for source-based routing, see “Configuring Traffic Filters for Source-Based Routing,” on page 3-10.

Responding to Proxy ARP Requests

By default, AHB receives ARP requests from ATM-attached hosts. When the AHB router receives an ARP request, it responds to this request with its own hardware address as the target MAC address. You must enable proxy ARP separately on each circuit.

ATM Half-Bridge Overview

When proxy ARP is enabled, the AHB router responds to ARP requests if all of the following conditions are true:

• The ARP request receiv ed by AHB is not a self-ARP request (tha t is , the ho st

• The host’s (sender) address is already in the bridge table or can be learned

• The target host address either is in the host table and has a different

For informat ion about conf iguring p roxy ARP, see “Enabling and Disabl ing Proxy ARP on a Circuit” on page 3-10.

308611-14.00 Rev 00

IP address equals the target IP address or the source address equals 0.0.0.0).

from this packet (unsecure mode enabled).

circuit VPI/VCI, or the target host address is not in the bridge table.

1-11

Configuring ATM Half-Bridge Services

Using Inbound Packet Filtering

AHB uses inbound pack et f ilterin g to forw ard b ridge pack ets i t recei v es from CPE hosts on an AHB interface, regardless of whether an entry exists in the bridge table for that CPE host. The AHB interface must be an ATM service record with LLC/SNAP encapsulation. For information about configuring inbound packet filtering, see “Enabling and Disabling Inbound Packet Filtering” on page 3-7.

1-12

308611-14.00 Rev 00

Chapter 2

Starting AHB Services

This chapter provides instructions for starting AHB services with the default configuration values supplied by Nortel Networks.

This chapter includes the following information:

Topic Page

Network Planning Considerations 2-1 AHB Configuration Requirements 2-1 Configuring AHB Services 2-5 Configuring a DHCP/BootP Relay Agent 2-10

Network Planning Considerations

Before you configure AHB, ensure that you have the following:

• The VPI/VCI numbers (ATM) used in your network configuration

• The ATM circuit names that you configured

• A minimum of 8 MB of memory on the router for ARE processor modules

AHB Configuration Requirements

Before you can configure AHB on the router, you must:

• Prepare a configuration file.

• Configure an IP interface on the router.

• Configure circuitless IP on the router.

308611-14.00 Rev 00

2-1

Configuring ATM Half-Bridge Services

Preparing a Configuration File

To create a configuration file for AHB, complete the following tasks:

You do this System responds

Site Manager Procedure

1. Choose

2. Choose

3. Choose

Dynamic.

4. Select the configuration file and click on

5. Choose either the BLN or BCN router model and cli ck on

Tools. Configuration Manager.

Local File, Remote File

Confirm

, or

The Tools menu opens. The Configuration Manager window

opens. Site Manager prompts you for the

configuration file you want to open. The Configuration Manager window

opens, displaying the router models. The Module List opens.

If you have ques tions about ho w to perfo rm any of these pre liminary task s, refer to Configuring and Managing Routers Using Site Manager.

set

The Technician Interface allows you to modify parameters by issuing

commit

commands with the managemen t inf ormati on base (MIB) obj ect I D. This

and

process is equivalent to modifying parameters using Site Manager. For more information about using the Technician Interface to access the MIB,

refer to Using Technician Interface Software.

Caution:

Nortel Networks strongly recommends that you use the Technician Interface f or very minor MIB ad jus tments only. The Tech nic ia n In te rface does not validate parameter entries. Entering an invalid value can corrupt your configuration.

2-2

Proceed to the next section to configure an IP interface on the router.

308611-14.00 Rev 00

Configuring an IP Interface on the Router

You must configure an IP interface on a non-ATM/AHB interface. This can be a LAN interface or a frame relay interface. You use this IP interface address as the associated IP interface when defining the unnumbered IP circuit for the AHB router.

To configure an IP interface on the router, begin at the Module List window and complete the following tasks:

Site Manager Procedure

You do this System responds

Starting AHB Services

1. In the Module List, choose a (for example, Quad Ethernet).

2. Click on a example, XCVR1).

3. Supply a default circuit name) and click on OK.

4. Select IP, then click on OK. The IP Configuration window opens.

5. Specify a valid IP address in dotted-decimal no tation f or the parameter (for example, 1.1.1.1).

Click on description on page A-15.

6. Accept the default values for the follow ing parameters:

•

Click on descriptions on page A-15.

7. Click on OK. You return to the Configuration Manager

link module connector

circuit name

or see the parameter

Help

Subnet Mask Transmit Bcast Addr UnNumbered Assoc Address

or see the parameter

Help

link module

(or accept the

IP address

(for

The Add Circuit List window opens.

The Select Protocols window opens.

window.

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2-3

Configuring ATM Half-Bridge Services

Configuring Circuitless IP on the Router

To operate AHB, you must configure unnumbered IP interfaces on the router and assign an associated IP address to each interface. You can elect to use the circuitless IP address as the associated address for unnumbered interfaces.

AHB uses unnumbered interfaces because not all hosts attached via the ATM circuit are on the same I P networ k. Furthermor e, a host may cha nge its IP ne twork over time (due to subscribing with different service providers), and it would be inconvenient to move the PVC for that host each time its network IP address changes.

When you configure a circuitless IP interface, note the following:

• You can configure only one circuitless IP interface per router.

• You must assign a unique IP address and subnetw ork number t o the cir cuitless IP interface.

A circuitless IP interface has an IP address that is not mapped to the address of a specific circuit. Thus, if one or more of the router’s IP interfaces becomes disabled, this circuitless feature ensures that the router is always reachable using the circuitless interface address, as long as a viable path to the router exists.

2-4

For more information about circuitless interfaces, see Configuring IP, ARP, RARP, RIP, and OSPF Services.

To configure a circuitless IP interface on the router, begin at the Configuration Manager wind ow and complete the following tasks:

Site Manager Procedure

You do this System responds

1. In the Configuration Manager window, choose

2. Choose

3. Choose

4. Choose

Protocols

. The IP menu opens.

Circuitless IP Create

. The Circuitless IP menu opens.

. The IP Configuration window opens.

The Protocols menu opens.

(continued)

308611-14.00 Rev 00

Starting AHB Services

Site Manager Procedure

You do this System responds

5. Specify a unique IP address in dotted-decimal no tation f or the parameter (for example, 250.225.2.2).

Click on description on page A-15.

6. Specify a valid subnet mask for the

Subnet Mask

255.255.255.0). Click on

description on page A-15.

7. Click on OK. Site Manager saves the circuitless IP

or see the parameter

Help

parameter (for example,

or see the parameter

Help

IP address

(continued)

interface, and opens a special Select Protocols window that lists the protocols that you can configure on a circuitless interface.

Go to the next section to configure AHB services on the router.

Configuring AHB Services

Configuring AHB services involves:

• Creating an ATM interface

• Adding an LLC/SNAP service record for PVCs

• Adding AHB on an LLC/SNAP service record

• Adding PVCs to the LLC/SNAP service record on an ATM interface

• Configuring a BootP relay agent Before configuring AHB, refer to Configuring and Managing Routers with Site

Manager for instructions about the Site Manager configuration tool and how to work with configuration files.

308611-14.00 Rev 00

2-5

Configuring ATM Half-Bridge Services

Creating an ATM Interface

To create an ATM interface, complete the following tasks:

You do this System responds

Site Manager Procedure

1. In the M odule Li st, cho ose an

module

2. Click on an (labeled ATM1).

3. Supply a circuit name (or accept the default circuit name) and click on OK.

4. Change the parameter to

Click on description on page A-19.

You disable ATM signaling because AHB runs only on PVCs, not SVCs.

5. Click on OK. The Edit ATM Connector window opens.

(for example, ARE OC-3 MM).

ATM link module connector

Enable ATM Signaling

Disable

Help

or see the parameter

ARE ILI link

Go to the next section to add an LLC/SNAP service record to the ATM interface that you just created.

Adding an LLC/SNAP PVC Service Record

When you add a service record to an ATM interface, you must specify the data encapsulation type and virtual connection it uses. AHB requires that you add the LLC/SNAP data encapsulat ion type an d the circu it (PVC) conne ction type for this service record.

The Add Circuit window opens.

The Initial ATM Signaling Config window opens.

Site Manager changes the value of this parameter.

2-6

Caution:

You cannot edit the Data Encapsulation Type or Virtual Connection Type parameter once you assign it to a service record. However, you can edit the Data Encapsulation Type for individual PVCs.

For an expl anation of the dif ferent data encapsula tion types and rul es for assigni ng data encapsulation, refer to Configuring ATM Services.

308611-14.00 Rev 00

Starting AHB Services

To add an LLC/SNAP service record, complete the following tasks:

Site Manager Procedure

You do this System responds

1. In the Edit ATM Connector window, click on

Service Attributes

2. Click on

3. Click on

Add.

OK.

The ATM Service Records List window opens.

The ATM Service Record Parameters window opens, displaying default values for the Data Encapsul atio n type and Virtual Connector type.

Because you disabled ATM signaling when you created the circuit, the ATM Service Record Parameters window automatically changes the default for the Data Encapsulation Type parameter to Logical Link Control/Subnetwork Access Protocol (LLC/SNAP) and the Virtual Connection Type parameter to PVC.

The ATM service information appears in the ATM Service Record List and the Select Protocols window opens.

Go to the next section, “Adding AHB to the LLC/SNAP Service Record

Adding AHB to the LLC/SNAP Service Record

When adding AHB services to an LLC/SNAP service record, remember the following:

.”

• A PVC type service record requires that you add at least one PVC for the

• Each service record globally controls all protocols for any PVCs that it

308611-14.00 Rev 00

service record to operate.

contains.

2-7

Configuring ATM Half-Bridge Services

To add AHB to an L LC/SNAP service record, complete the following tasks:

You do this System responds

Site Manager Procedure

1. In the Select Protocols window, click on

AHB.

2. Click on

3. Specify an unnumbered interface address (0.0.0.0) for the

Click on description on page A-15.

4. Specify the associate d numbered circuit address for the

Address

circuitless IP interface address. Click on

description on page A-16.

5. Click on OK. The ATM Half-Bridge Configuration

6. Accept the AHB default configurat ion values and click on OK.

OK.

IP Address

or see the parameter

Help

UnNumbered Assoc

parameter. This may be a

or see the parameter

Help

parameter.

The Configurati on Manager auto matically highlights IP and BootP, add ing these protocols to the service record.

The IP Configuration window opens, prompting you to specify IP configuration parameters.

window opens. The ATM Virtual Channel Link window

opens.

2-8

Next, add PVCs to the LLC/SNAP service record on the ATM interface.

308611-14.00 Rev 00

Adding PVCs to the LLC/SNAP PVC Service Record

T o add PVCs to the LLC/SNAP service record on the ATM interface, complete the following tasks:

Site Manager Procedure

You do this System responds

Starting AHB Services

1. In the ATM Virtual Channel Link window, click on

2. Supply the following information:

•A

the cell header, identifies the virtual path of the PVC. The header can contain a maximum of 8 VPI bits for a UNI connection. This bit range allows for path identifiers from 0 to 255.

•A

the cell header, identifies the virtual channel of the PVC. The header can contain a maximum of 16 VCI bits. This bit range allows for channel identifiers from 0 to 65535.

Click on descriptions on page A-23.

3. Click on OK. The ATM Virtual Channel Link window

4. To add another PVC with the default configuration, repe at ste ps 1 through 3.

5. Click on

6. Click on

7. Click on

Add

This number, which is part of

VPI

This number, which is part of

VCI

or see the parameter

Help

. The ATM Service Records List window

Done

. The Edit ATM Connector window opens.

Done

. You return to the Configuration Manager

Done

The ATM Virtual Channel Link Parameters window opens.

opens. For information about changing parameters in the ATM Virtual Channel Link window, refer to

opens.

window.

Appendix B.

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2-9

Configuring ATM Half-Bridge Services

Note:

Following the recommendation of the ATM Forum, virtual channel

identifiers from 0 to 31 are reserved for signaling and added functionality.

Next, you must configure BootP to def ine a forwarding path between a router and a BootP/DHCP server on the network.

Configuring a DHCP/BootP Relay Agent

To allow the AHB router to successfully forward DHCP packets from CPE hosts to a DHCP server on the networ k, you must conf igure a Boot P relay agent on both the unnumbered ATM/IP interface and an associated numbered interface. AHB does this automatically when you add AHB to the ATM service record. You also must define a forw ardi ng path bet ween the AHB router and a DHCP ser v er on the network. You establish this forwarding path using one or both of the following methods:

• Configure one or more BootP forwarding IP interfaces on the router. You define one IP interface to receive DHCP request pac k et s f ro m t he r emot e

CPE hosts and another to transmit (broadcast) DHCP request packets to the DHCP server.

• Configure one or more BootP preferred se rver s on an IP interf ace on the AHB router .

You define one IP interface to receive DHCP request pac k et s f ro m t he r emot e CPE hosts and to then unicast the requests directly to the DHCP server.

Creating a BootP Relay Agent Forwarding Interfaces

You create a BootP relay agent forwarding table for the IP interfaces that you configure to receive the incoming DHCP request packets and to forward the outgoing DHCP request packets to the DHCP server on the network. The BootP relay agent forwards DHCP request packets based on the IP addresses of the interfaces in this table. For more information about configuring a forwarding table, refer to Configuring SNMP, BootP, and DHCP Services.

2-10

308611-14.00 Rev 00

Starting AHB Services

Site Manager req uires tha t you speci fy input and out put addres ses to conf igure th e BootP relay agent on the AHB router. The input IP address is the ATM unnumbered interface on which the DHC P request packet is received. The ATM unnumbered interfa ce address appe ars in the BootP Rel ay Agent table. I ts last four digits are 0.0.0 <cir c uit_number >, wher e circuit number is the unnumbered cir cuit that you configured.

The output IP address is the address of the local IP interface to which the DHCP packets are forwarded.

To create a BootP relay agent forwarding table, complete the following tasks:

Site Manager Procedure

You do this System responds

1. In the Configuration Manager window, choose

2. Choose IP. The IP menu opens.

3. Choose

4. Choose

5. Click on

6. Click on

7. Add a BootP forwarding entry by setting the following parameters:

• Input IP Address

• Output IP Address

Click on descriptions on page A-11.

8. Click on OK. The BOOTP Relay Agent Forwarding

9. Click on

10. Click on

Protocols

BootP Relay Agent Interface Table

Forward I/F

Add

or see the parameter

Help

Done

. The BOOTP menu opens.

. The BOOTP Relay Agent Forwarding

. The BOOTP Addresses window opens.

. The BOOTP Relay Agent Interface Table

. You return to the Configuration Manager

The Protocols menu opens.

. The BOOTP Relay Agent Interface Table

window opens, displaying the IP interfaces that you configured on the AHB router (ATM PVCs, circuitless IP interface, and so forth).

Table window opens.

window opens.

window.

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2-11

Configuring ATM Half-Bridge Services

Configuring BootP Preferred Servers

You can configure a BootP preferred server by specifying the IP address of the relay agent on the router and the IP address of the target server. You configure a preferred server when you know the IP address of the DHCP server to which you want to send a DHCP request.

Specifying the Relay Agent IP Address

The relay agent I P address is the inter f ace that you want to receive DHCP packets from a CPE host. If you configured BootP on an unnumbered interface (ATM/AHB interface), specify the associated numbered interface address for the relay agen t IP address.

To specify the relay agent IP address, complete the following ta sks:

Site Manager Procedure

You do this System responds

1. In the Configuration Manager window, choose

2. Choose IP. The IP menu opens.

3. Choose

4. Choose

5. Click on

6. Click on

7. Set the parameter. Click on parameter description on page A-14.

8. Click on OK.

9. Click on

Protocols

BOOTP Relay Agent Interface Table

Pref Serv

Add

Relay Agent IP Address

Done

. The BOOTP menu opens.

. The BOOTP Relay Agent Preferred

. The BOOTP Preferred Server

or see the

Help

. You return to the Configuration Manager

The Protocols menu opens.

. The BOOTP Relay Agent Interface Table

window opens.

Server Table opens.

Configuration window opens.

window.

2-12

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Starting AHB Services

Specifying the Target Server IP Address

After you specify the relay agent IP address, you must specify the IP address of the DHCP server that should receive the DHCP packet from the BootP relay agent.

To specify the target server IP address, complete the following tasks

Site Manager Procedure

You do this System responds

1. In the Configuration Manager window, choose

2. Choose IP. The IP menu opens.

3. Choose

4. Choose

5. Click on

6. Click on

7. Set the on on page A-15.

8. Click on OK.

9. Click on

Protocols

BOOTP Relay Agent Interface Table

Pref Serv

Add

Target IP Server

or see the parameter description

Help

Done

. The BOOTP menu opens.

. The BOOTP Relay Agent Preferred

. The BOOTP Preferred Server

parameter. Click

. You return to the Configuration Manager

The Protocols menu opens.

. The BOOTP Relay Agent Interface Table

window opens.

Server Table opens.

Configuration window opens.

window.

308611-14.00 Rev 00

2-13

Chapter 3

Customizing AHB Services

When you first configure AHB services, default values are in effect for all parameters (see parameter descriptions in Appendix A). You may want to change these values, depending on the requirements of your network.

This chapter provides information about how to customize AHB to use it effectively on your network. This chapter includes the following topics:

Topic Page

Modifying the AHB Configuration 3-1 Modifying AHB Circuits 3-8 Configuring Traffic Filters for Source-Based Routing 3-10 Deleting AHB from the Router 3-11

Modifying the AHB Configura tion

To change the way AHB operates on the router, you can modify the AHB global parameters in the Edit ATM Half-Bridge Global Parameters window (see Figure A-1 on page A-2).

Enabling and Disabling AHB

By default, AHB forwards packets to and from ATM PVCs when you enable the AHB function on the router. When you disable AHB, you prevent AHB from forwarding packets to and from ATM PVCs.

308611-14.00 Rev 00

3-1

Configuring ATM Half-Bridge Services

To enable and disable AHB forwarding on the router, complete the following tasks:

You do this System responds

Site Manager Procedure

1. In the Configuration Manager window, choose

2. Choose

3. Choose

4. Choose

5. Set the or see the parameter description in Appendix A.

Protocols

. The IP menu opens.

IP AHB

Global

Enable

. The AHB menu opens.

. The Edit ATM Half-Bridge Global

parameter. Click on Help

Setting the Auto Learn Method

You can determine the method by which AHB automatically learns new bridge entries on the router by configuring the auto learning method. You can configure AHB in one of the following learning modes:

•Secure

• Unsecure

•Both

•None

The Protocols menu opens.

Parameters window opens.

3-2

By default, the auto learn method is set to Both. This means that AHB will learn new bridge entries either securely or unsecurely.

If you set the learning mode to Secure or Both, AHB learns new bridge entries from the DHCP reply packets sent on the AHB-configured interface. Entries learned in secure mode always take precedence over entries learned in unsecure mode.

If you set the learning mode to Unsecure or Both, AHB learns new bridge entries from IP and ARP packets received on the AHB-configured interface.

308611-14.00 Rev 00

Customizing AHB Services

To set the auto learn method by which AHB learns bridge entries, complete the following tasks:

Site Manager Procedure

You do this System responds

1. In the Configuration Manager window, choose

2. Choose

3. Choose

4. Choose

5. Set the Click on description on page A-3.

6. Click on

Protocols

. The IP menu opens.

IP AHB

Global

Auto Learn Method

Help

OK.

. The AHB menu opens.

. The Edit ATM Half-Bridge Global

or see the parameter

Configuring a Local AHB Init File

AHB Init files are ASCII data files that you can use to manually add bridge table entries and or configure PVCs on an AHB interface. You create the init files locally, but must store them on the rou ter’s flash memory card. AHB reads the i nit files from the router’s flash memory when the router boots.

The AHB init files contain an extra flag on each entry that indicates where AHB should create the corresponding PVC identified in the bridge entry, if it does not already exist.

The Protocols menu opens.

Parameters window opens.

parameter.

You return to the Configuration Manager window.

Sample Init File

In the AHB init file, there is a section for each router slot that has configured bridge entries. Slots that do not contai n hosts do not need a se ction he ader. Within a section, there is one line for each bridge entry.

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3-3

Configuring ATM Half-Bridge Services

A sample init file (a hb.dat) follows:

[SLOT 3]

1.3.1.32 255.255.255.0 4 409600 0 0 aaaa030080c200070000112233445566aabbccdde eff0800

1.3.2.32 255.255.255.0 4 409600 0 0 aaaa030080c200070000778899001122aabbccdde eff0800

[SLOT 4]

1.4.2.32 255.255.255.0 5 409600 0 0 aaaa030080c200070000998877665544aabbccdde eff0800

The bridge entry fields (separated by spaces) are:

• Field 1 = host IP address (dotted-decimal)

• Field 2 = host subnet mask (dotted-decimal)

• Field 3 = ATM circu it number (dec imal)

• Field 4 = PVC VPI/VCI (decimal, VPI in bits 0-11, VCI in bits 12-23)

• Field 5 = reference VPI/VCI (decimal)

• Field 6 = host flag s (decimal, bit field)

3-4

• Field 7 = bridge header (hex, 1483 SNAP/LLC + ethernet header) The host flag bits which can be configured are:

• Bit 0 = no protocol address, do not add bridge entry to table

• Bit 3 = add new PVC (VPI/VCI in field 4) based on reference PVC

• Bit 4 = do not forward packets that match this IP address

• Bit 7 = if set, indi cates that host entry sho uld be deleted The bridge header has the following format:

• Octets 00-09 = encapsulate for 1483 bridged Ethernet packet

• Octets 10-15 = destination MAC address

• Octets 16-21 = source MAC address

• Octets 22-23 = protocol ID (0x800 for IP) The reference VPI/VCI identifies a preconfigured ATM PVC whose parameters

are used as a template when AHB creates a new PVC.

308611-14.00 Rev 00

Customizing AHB Services

To specify the name of the local init file you want to use, complete the following tasks:

Site Manager Procedure

You do this System responds

1. In the Configuration Manager window, choose

2. Choose

3. Choose

4. Choose

5. Set the

or see the parameter description on

Help

page A-4.

6. Click on

Protocols

. The IP menu opens.

IP AHB

Global

Local Init File

. The AHB menu opens.

. The Edit ATM Half-Bridge Global

parameter. Click on

. You return to the Configuration Manager

Specifying an Alternate Init File

You can create an alternate init file (backup) as a safeguard in case the local init file f ails t o load pr operl y when the r out er boot s. You should co py th e alte rna te ini t file to a different flash memory card on the AHB router.

When you boot the AHB router, it attempts to read the local init file. If the local init file is null, or if AHB cannot read the file, it then reads the alternate init file.

The Protocols menu opens.

Parameters window opens.

window.

308611-14.00 Rev 00

3-5

Configuring ATM Half-Bridge Services

To specify the name of the alternate init file you want to use, complete the following tasks:

You do this System responds

Site Manager Procedure

1. In the Configuration Manager window, choose

2. Choose

3. Choose

4. Choose

5. Set the Click on description on page A-4.

6. Click on

Protocols

. The IP menu opens.

. The AHB menu opens.

AHB

. The Edit ATM Half-Bridge Global

Global

Alternate Init File

or see the parameter

Help

. You return to the Configuration Manager

Specifying the Debug Level

You can display the le v el of de b ug messag ing you want the AHB rout er to di splay in its log file by spec ifying a value for the Debug Level parameter.

By default, the debug level is set to 0, meaning that AHB disables all debug messages. You can specify a debug level value from 1 to 5. Specifying a higher value causes AHB to display more detailed debug messages.

To specify the debug level, complete the following tasks:

The Protocols menu opens.

Parameters window opens.

parameter.

window.

3-6

Site Manager Procedure

You do this System responds

1. In the Configuration Manager window, choose

2. Choose

3. Choose

4. Choose

Protocols

. The IP menu opens.

IP AHB

Global

. The AHB menu opens.

. The Edit ATM Half-Bridge Global

The Protocols menu opens.

Parameters window opens.

(continued)

308611-14.00 Rev 00

Customizing AHB Services

Site Manager Procedure

You do this System responds

5. Set the

or see the parameter description on

Help

page A-4.

6. Click on

Debug Level

. You return to the Configuration Manager

parameter. Click on

(continued)

window.

Enabling and Disabling Inbound Packet Filtering

By default, inbound packet filtering is disabled on the AHB router. This means that AHB forwards bridge packets it receives from CPE hosts, regardless of whether a table entry exists in the bridge table for that host.

When you enable inbound packet filtering on the AHB router, AHB verifies that the source address in the IP packet is contained in the bridge table and that it corresponds to the circuit and virtual connection identification number (VCID) contained in the AHB bridge table. This is a check to ensure that the packets received by the AHB router are valid.

To enable and disable inbound packet filtering on the AHB router, complete the following tasks:

You do this System responds

1. In the Configuration Manager window,

2. Choose

3. Choose

4. Choose

5. Set the

6. Click on

308611-14.00 Rev 00

Site Manager Procedure

choose

parameter. Click on parameter description on page A-5.

Protocols

. The IP menu opens.

IP AHB

Global

Inbound Packet Filtering

. The AHB menu opens.

. The Edit ATM Half-Bridge Global

or see the

Help

. You return to the Configuration Manager

The Protocols menu opens.

Parameters window opens.

window.

3-7

Configuring ATM Half-Bridge Services

Modifying AH B Circuit s

You can modify AHB circuits by changing the AHB circuit parameters located in the ATM Half-Bridge Circuit List window (refer to Appendix A). You may need to modify AHB circuit characteristics after you configure multiple PVCs on an ATM interface, and you have configured AHB on this interfa ce. These paramet ers include:

• Enable

• Learned Host Subnet Mask

• Enabling Proxy ARP

Enabling and Disabling an AHB Circuit

You enable the bridging of packets on an AHB circuit when you configure AHB interfaces on the router. To disable the bridging of packets on AHB interfaces, set the Enable parameter to Disable.

To enable and disable the bridging of packets on an AHB circuit, complete the following tasks:

3-8

Site Manager Procedure

You do this System responds

1. In the Configuration Manager window, choose

2. Choose

3. Choose

4. Choose

5. Set the or see the parameter description on page A-6.

6. Click on

7. Click on

Protocols

. The IP menu opens.

IP AHB Circuit List

Enable

Apply Done

. The AHB menu opens.

. The Edit ATM Half-Bridge Circuit List

parameter. Click on

. You return to the Configuration Manager

Help

The Protocols menu opens.

window opens.

window.

308611-14.00 Rev 00

Specifying the Subnet Mask for the Learned Host

If you set the learning method on the ATM interface to Unsecure or Both, you must specify a subnet mask for a dynamically learned host. AHB uses the subnet mask to identify th e host’ s network and to add r outes to the IP routing table based on the host’s IP address.

If you specify 0.0.0.0 (default) as the subnet mask for learned hosts, then AHB uses the natural class (A, B, C) subnet mask.

To specify the subnet mask for the learned host, complete the following tasks:

Site Manager Procedure

You do this System responds

Customizing AHB Services

1. In the Configuration Manager window, choose

2. Choose

3. Choose

4. Choose

5. Set the parameter. Click on parameter description on page A-7.

6. Click on

7. Click on

Protocols

. The IP menu opens.

IP AHB Circuit List

Learned Host Subnet Mask

Apply Done

. The AHB menu opens.

. The Edit ATM Half-Bridge Circuit List

or see the

Help

. You return to the Configuration Manager

The Protocols menu opens.

window opens.

window.

308611-14.00 Rev 00

3-9

Configuring ATM Half-Bridge Services

Enabling and Disabling Proxy ARP on a Circuit

By default, proxy ARP i s e nabl ed on the AHB circuit when you co nfigure it. This tells the AHB router to respond to ARP requests from ATM-atta ched hosts with its own hardware address as the target MAC address.

You must separately enable or disable proxy ARP on each AHB circuit on the router.

To enable and disable proxy ARP on each AHB circuit, complete the following tasks:

Site Manager Procedure

You do this System responds

1. In the Configuration Manager window, choose

2. Choose

3. Choose

4. Choose

5. Set the Click on description on page A-7.

6. Click on

7. Click on

Protocols

. The IP menu opens.

IP AHB Circuit List.

Enable Proxy ARP

Help

Apply Done

. The AHB menu opens.

parameter.

or see the parameter

. You return to the Configuration Manager

The Protocols menu opens.

The Edit ATM Half-Bridge Circuit List window opens.

window.

Configuring Traffic Filters for Source-Based Routing

The AHB router may use source-based routing to ensure that packets sent from a CPE host travel to the correct ISP gateway first, regardless of its destination address. The ISP gateway can be an edge router directly connected to an AHB router via a WAN interface (frame relay, PPP) or a router located within the ISP domain.

You configure source-based routing by creating an IP traffic filter whose action is “forward to next hop.” You must specify the ISP gateway address (or a virtual address within the ISP domain) as the next-hop address.

3-10

308611-14.00 Rev 00

For detailed information about creating traffic filters for source-based routing, refer to Configuring Traffic Filters and Protocol Prioritization.

Deleting AHB from the Router

To delete AHB from the router, complete the following tasks:

Site Manager Procedure

You do this System responds

Customizing AHB Services

1. In the Configuration Manager window, choose

2. Choose

3. Choose

4. Choose

Protocols

. The IP menu opens.

IP AHB

Delete AHB

. The AHB menu opens.

. You return to the Configuration Manager

The Protocols menu opens.

window.

308611-14.00 Rev 00

3-11

Appendix A

AHB, BootP/DHCP, IP, and ATM

Parameter Descriptions

This appendix contains reference information about customizing AHB global configuration and AHB circuit parameters. It also contains a subset of parameter descriptions for BootP/DHCP, IP, and ATM that you can use to configure AHB.

Topic Page

AHB Global Parameters A-2 AHB Circuit Parameters A-6 BootP Relay Agent Interface Table Parameters A-8 BootP Address Parameters A-10 BootP Relay Agent Preferred Server Table Parameters A-12 BootP Preferred Server Configuration Parameters A-14 IP Configuration Parameters A-15 ATM Interface Parameter Descriptions A-17 ATM Service Record Parameter Descriptions A-19 ATM Virtual Channel Lin k Parameter Descrip tions A-23

For each parameter, this appendix provides the following information:

• Parameter name

• Configuration Manager menu path

• Default setting

• Valid parameter options

• Parameter function

308611-14.00 Rev 00

A-1

Configuring ATM Half-Bridge Services

• Instructions for setting the parameter

• Management information base (MIB) object ID The Technician Interface allows you to modify parameters by issuing

commit commands with the MIB object ID. This process is equivalent to

modifying parameters using Site Manager. For more information about using the Technician Interface to access the MIB, refer to Using Technician Interface Software.

Caution:

The Technician Interface does not verify the validity of your

parameter values. Entering an invalid value can corrupt your configuration.

AHB Global Parameters

Use the following guidelines to configure AHB global parameters in the Edit ATM Half-Bridge Global Parameters window (Figure A-1 Half-Bridge Global Parameters window contains parameters that allow you to customize AHB operation.

set and

). The Edit ATM

A-2

Figure A-1. Edit ATM Half-Bridge Global Parameters Window

308611-14.00 Rev 00

AHB, BootP/DHCP, IP, and ATM Parameter Descriptions

The AHB global parameter descriptions follow.

Parameter: Enable

Path: Configuration Manager > Protocols > IP > AHB > Global

Default: Enabled

Options: Enable

Function: Enables or disables AHB packet forwarding to and from ATM PVCs.

Instructions: Select Disable to disable AHB on this interface without deleting it. Select

Enable to reenable AHB services if you previously disabled it.

MIB Object ID: 1.3.6.1.4.1.18.3.5.9.13.1 #2

Parameter: Auto Learn Method

Path: Configuration Manager > Protocols > IP > AHB > Global

Default: None

Options: Secure

Function: Specifies the method by which AHB dynamically learns new bridge entries on

the router.

Instructions: By default, the au to learn metho d is set to Both. This means t hat AHB will learn

new bridge entries either securely or unsecurely.

Disabled

Unsecure | Both | None

If you set the learning mode to Secure or Both, AHB learns new bridge entries from the DHCP reply packets sent on the AHB-configured interface. Entries learned in secur e mode always take precedence over entries learned in unsecure mode.

If you set the learning mode to Unsecure or Both, AHB learns new bridge entries from IP and ARP packets received on the AHB-configured interface.

MIB Object ID: 1.3.6.1.4.1.18.3.5.9.13.1 #3

308611-14.00 Rev 00

A-3

Configuring ATM Half-Bridge Services

Parameter: Local Init F ile

Path: Configuration Manager > Protocols > IP > AHB > Global

Default: None

Options: None

Function: Specifies a local ASCII data file into w hich you can ad d bridge table entries for

configuring PVCs on an AHB interface. You create init files locally, but you must store them on the router’s flash memory card. AHB loads the init files when the router boots.

Instructions: Specify the name of the init file you want to use. Be sure to copy the file to the

router’s flash memory so the router can boot with this file.

MIB Object ID: 1.3.6.1.4.1.18.3.5.9.13.1 #4

Parameter: Alternate Init File

Path: Configuration Manager > Protocols > IP > AHB > Global

Default: None

Options: None

Function: Specifies an alternate init file (backup) as a safeguard in case the local init file

fails to load properly when the router boots.

Instructions: Specify the alternate init file name.

MIB Object ID: 1.3.6.1.4.1.18.3.5.9.13.1 #5

Parameter: Debug Level

Path: Configuration Manager > Protocols > IP > AHB > Global

Default: 0

Options: Recommended values are from 1 to 5

Function: Specifies the level of debug messaging you want to display in the log file for

AHB.

Instructions: Enter the debug messaging level you want.

MIB Object ID: 1.3.6.1.4.1.18.3.5.9.13.1 #6

A-4

308611-14.00 Rev 00

AHB, BootP/DHCP, IP, and ATM Parameter Descriptions

Parameter: Inbound Packet Filtering

Path: Configuration Manager > Protocols > IP > AHB > Global

Default: Disabled

Options: Enabled

Disabled

Function: By default, inbound packet filtering is disabled on the AHB router. This means

that AHB forwards bridge packets it receives from CPE hosts, regardless of whether a table entry exists in the bridge table for that host.

When you enable inbound packe t fi lterin g on the AHB router, AHB verifies that the source address in the IP packet is contained in the bridge table and that it corresponds to the circuit and virtual connection identification number (VCID) contained in the AHB bridge table. This is a check to ensure that the packets received by the AHB router are valid.

Instructions: Choose Enable to enable packet fi ltering on the AHB router. Choose Disable to

disable packet filtering on the AHB router.

MIB Object ID: 1.3.6.1.4.1.18.3.5.9.13.1 #7

308611-14.00 Rev 00

A-5

Configuring ATM Half-Bridge Services

AHB Circuit Para meters

Use the following guidelines to configure AHB Circuit parameters in the ATM Half-Bridge Circuit List window (Figure A -2

Figure A-2. ATM Half-Bridge Circuit List

The AHB circuit list parameters follow.

Parameter: Enable

Path: Configuration Manager > Protocols > IP > AHB > Circuit List

Default: Enabled

Options: Enabled

Function: Enables or disables AHB packet forwarding to and from CPE hosts connected

via this circuit.

Instructions: Choose Enable to enable AHB packet forwarding on this circuit. Choose

Disable to disable packet forwarding on this AHB circuit.

MIB Object ID: 1.3.6.1.4.1.18.3.5.9.13.2.1 #2

A-6

Disabled

308611-14.00 Rev 00

AHB, BootP/DHCP, IP, and ATM Parameter Descriptions

Parameter: Learned Host Subnet Mask

Path: Configuration Manager > Protocols > IP > AHB > Circuit List

Default: 0.0.0.0

Options: None

Function: Applies only when you set the au to learni ng method to Unsec ure or Both. When

you specify a subnet mask for the learned host, AHB uses this subnet mask specified i n t he MI B ent r y wfAh bCir cui tE ntr y.afAhbCctDefSubNetmask<cct> , where <cct> represents the circuit on which the host is learned.

Instructions: Specify a valid subnet mask for the learned host. If you specify 0.0.0.0

(default), then AHB uses the natural class (A,B,C) subnet mask.

MIB Object ID: 1.3.6.1.4.1.18.3.5.9.13.2.1 #4

Parameter: Enable Proxy ARP

Path: Configuration Manager > Protocols > IP > AHB > Circuit List

Default: Enable

Options: Enabled

Disabled

Function: Specifies whether or not the AHB router responds to ARP requests sent from

ATM-attached hosts on the remote network.

Instructions: Choose Enable to allows AHB to respond to ARP requests from ATM-attached

hosts. Choose Disable to prevent AHB from responding to ARP requests from AHB-attached hosts.

MIB Object ID: 1.3.6.1.4.1.18.3.5.9.13.2.1 #5

308611-14.00 Rev 00

A-7

Configuring ATM Half-Bridge Services

BootP Relay Agent Interface Table Parameters

Use the following guidelines t o configure DHCP parameters in the BOOTP Relay Agent Interface Table window (Figure A-3 that you configured on the AHB router. It contains parameters that allow you to change the way the BootP relay agent operates.

). This table lists all the IP interfaces

A-8

Figure A-3. BOOT P Relay Agent Interface Table Window

The BOOTP relay agent interface table window parameter descriptions follow.

308611-14.00 Rev 00

AHB, BootP/DHCP, IP, and ATM Parameter Descriptions

Parameter: Enable/Disable

Path: Configuration Manager > Protocols > IP > BOOTP > Relay Agent Interface

Table

Default: Enable

Options: Enable

Disable

Function: Specifies whet her BootP is active on the network i nterface.

Instructions: Select Enable to enable BootP on the network interface ; select Disable to

disable BootP on the network interface.

MIB Object ID: 1.3.6.1.4.1.18.3.5.3.8.3.1.1.2

Parameter: Hops

Path: Configuration Manager > Protocols > IP > BOOTP > Relay Agent Interface

Table

Default: 4

Options: 1 to 16 hops

Function: Specifies t he maximum number of hops from the CPE host to the DHCP se rver.

A hop is the logical distance between two devices. If the value in the hops field of a DHCP packet is gr eat er t han the number you spec if y f or th is pa rame ter, the router drops the packet.

Instructions: Accept the default of 4 hops or specify a number from 1 to 16.

MIB Object ID: 1.3.6.1.4.1.18.3.5.3.8.3.1.1.5

Parameter: Timeout Secs.

Path: Configuration Manager > Protocols > IP > BOOTP > Relay Agent Interface

Table

Default: 0

Options: 0 to 65535 seconds

Function: Specifies the minimum number of seconds that the router waits before

forwarding a DHCP packet. If the value in the seconds field of a DHCP packet is less than the value you specify for this parameter, the router drops the packet.

Instructions: Accept the default, 0, or specify a number from 1 to 65535.

MIB Object ID: 1.3.6.1.4.1.18.3.5.3.8.3.1.1.6

308611-14.00 Rev 00

A-9

Configuring ATM Half-Bridge Services

Parameter: Pass Through Mode

Path: Configuration Manager > Protocols > IP > BOOTP > Relay Agent Interface

Table

Default: BOOTP

Options: BOOTP

Function: Specifies whether the interface relays BootP, DHCP, or both BootP and DHCP

requests.

Instructions: Select BOOTP to relay BootP requests; select DHCP to relay DHCP requests;

select BOOTP and DHCP to relay both kinds of requests.

MIB Object ID: 1.3.6.1.4.1.18.3.5.3.8.3.1.1.16

DHCP | BOOTP and DHCP

BootP Address Parameters

Use the following guidelines to configure DHCP parameters in the BOOTP Addresses window. The BOOTP Addresses window (Figure A-4 parameters that allow you to specify the IP interface addresses (input/output) that you want to receive and forward DHCP packets.

) contains

A-10

Figure A-4. BOOTP Addresses Window

308611-14.00 Rev 00

AHB, BootP/DHCP, IP, and ATM Parameter Descriptions

To access the BOOTP Addresses window, complete the following tasks:

Site Manager Procedure

You do this System responds

1. In the Configuration Manager window, choose

2. Choose IP. The IP menu opens.

3. Choose

4. Choose

5. Click on

6. Click on

Protocols

BOOTP Relay Agent Interface Table

Forward I/F

Add

. The BOOTP menu opens.

. The BOOTP Relay Agent Forwarding

. The BOOTP Addresses window opens.

The Protocols menu opens.

. The BOOTP Relay Agent Interface Table

window opens. This window lists the IP interfaces that you configured on the router.

Table window opens.

The BootP address parameter descriptions follow.

Parameter: Input IP Address

Path: Configuration Manager > Protocols > IP > BOOTP > Relay Agent Interface

Table > Forward I/F > Add

Default: None

Options: Any valid IP address

Function: Specifies the IP interface that receives DHCP packets from CPE hosts.

Instructions: Enter the I P address of an i nterf ace that you want to rec ei ve DHCP p ack ets from

CPE hosts.

MIB Object ID: 1.3.6.1.4.1.18.3.5.3.8.3.2.1.3

308611-14.00 Rev 00

A-11

Configuring ATM Half-Bridge Services

Parameter: Output IP Address

Path: Configuration Manager > Protocols > IP > BOOTP > Relay Agent Interface

Table > Forward I/F > Add

Default: None

Options: Any valid IP address

Function: Specifies the IP interface that forwards DHCP packets to an external network.

Instructions: Enter the IP address of a numbered network interface that you want to send

DHCP packets to CPE hosts.

MIB Object ID: 1.3.6.1.4.1.18.3.5.3.8.3.2.1.4

BootP Relay Agent Preferred Server Table Parameters

Use the following guidelines to configure BootP preferred server parameters in the BOOTP Relay Agent Preferred Server Table window (Figure A-5 contains parameters that allow you to customize BootP relay agent preferred server functions.

). This table

A-12

Figure A-5. BOOTP Relay Agent Preferred Server Table Window

308611-14.00 Rev 00

AHB, BootP/DHCP, IP, and ATM Parameter Descriptions

The BootP relay agent preferred server para meters descriptions follow:

Parameter: Enable/Disable

Path: Configuration Manager > Protocols > IP > BOOTP > Relay Agent Interface

Table > Pref Se rv > Add

Default: Enable

Options: Enable

Function: Specifies whether the forwarding route is active.

Instructions: Select Enable to allow DHCP forwa rding through this route; select Di sable to

prevent DHCP forwarding through this route.

MIB Object ID: 1.3.6.1.4.1.18.3.5.3.8.3.3.1.2

Parameter: Target Name

Path: Configuration Manager > Protocols > IP > BOOTP > Relay Agent Interface

Table > Pref Se rv > Add

Default: None

Options: Any string of printable ASCII characters, up to 63 characters in length,

including embedded spaces

Function: Specifies the target server’s host name.

Instructions: To keep track of the names of DHCP serv ers , enter the target server’s hos t name.

MIB Object ID: 1.3.6.1.4.1.18.3.5.3.8.3.3.1.5

Disable

Parameter: Pass Through Mode

Path: Configuration Manager > Protocols > IP > BOOTP > Relay Agent Interface

Table > Pref Se rv > Add

Default: BOOTP

Options: BOOTP

Function: Specifies whether the interface relays BootP, DHCP, or both BootP and DHCP

requests.

Instructions: Select BOOTP to relay BootP requests; select DHCP to relay DHCP requests;

select BOOTP and DHCP to relay both kinds of requests.

MIB Object ID: 1.3.6.1.4.1.18.3.5.3.8.3.3.1.6

308611-14.00 Rev 00

DHCP | BOOTP and DHCP

A-13

Configuring ATM Half-Bridge Services

BootP Preferred Server Configuration Parameters

The BOOTP Preferred Server Configuration window (Figure A-6) contains parameters that a llo w you t o s pecif y the IP addre ss of the re lay a gent on the r outer and the IP address of the target server.

Figure A-6. BOOTP Preferred Server Configuration Window

The BootP preferred server configuration parameter descriptions follow.

Parameter: Relay Agent IP Address

Path: Configuration Manager > Protocols > IP > BOOTP > Relay Agent Interface

Table > Pref Se rv > Add

Default: None

Options: Any valid IP address

Function: Specifies the IP interface that receives DHCP packets from CPE hosts.

Instructions: Enter the IP address of a numbered network interface that you want to receive

DHCP packets from CPE hosts.

MIB Object ID: 1.3.6.1.4.1.18.3.5.3.8.3.3.1.3

A-14

308611-14.00 Rev 00

AHB, BootP/DHCP, IP, and ATM Parameter Descriptions

Parameter: Target Server IP Address

Path: Configuration Manager > Protocols > IP > BOOTP > Relay Agent Interface

Table > Pref Se rv > Add

Default: None

Options: Any valid IP address

Function: Specifies the address of the DHCP server that should receive DHCP packets.

Instructions: Enter the IP address of the DHCP server that should receive DHCP packets.

MIB Object ID: 1.3.6.1.4.1.18.3.5.3.8.3.3.1.4

IP Configuration Parameters

Parameter: IP Address

Path: Select IP from the Select Protocols window and click on OK.

Default: None

Options: 0.0.0.0 or any valid IP address

Function: Assigns a 32-b it IP address to the interface.

Instructions: Enter the IP addr ess of the int er f ace in dotted-decimal not at ion . Ente r 0.0.0.0 to

configure an unnumbered interface on the circuit.

MIB Object ID: 1.3.6.1.4.1.18.3.5.3.2.1.4.1.4

Parameter: Subnet Mask

Path: Select IP from the Select Protocols window and click on OK.

Default: None

Options: The Configuration Manager automatically calculates an appropriate subnet

mask, depending on the class of the network to which the interface connects. However, you can change the subnet mask with this parameter.

Function: Specifies the network and subnetwork portion of the 32-bit IP address.

Instructions: Either accept the assigned subnet mask or enter another subnet mask in

dotted-decimal notation. Enter 0.0.0.0 if you are configuring an unnumbered interface on the circuit.

MIB Object ID: 1.3.6.1.4.1.18.3.5.3.2.1.4.1.6

308611-14.00 Rev 00

A-15

Configuring ATM Half-Bridge Services

Parameter: Transmit Bcast Addr

Path: Select IP from the Select Protocols window and click on OK.

Default: 0.0.0.0

Options: 0.0.0.0 or any valid IP broadcast address

Function: Specifies the broadcast address that this IP subnet uses to broadcast packets.

Accepting 0 .0.0.0 for this parameter specifies that the IP router will use a broadcast address with a host portion of all 1s. Accepting 0.0.0.0 does not configure the router to use the address 0.0.0.0 to broadcast packets. For example, if you have IP address 123.1.1.1 and a subnet mask of 255.255.255.0, accepting the default value 0.0.0.0 configures the IP router to use the address

123.1.1.255 to broadcast packets. To set the explicit broadcast address of all 1s, enter 255.255.255.255 for this parameter.

Instructions: Accept the default, 0.0.0.0, unless the calculated broadcast address (host

portion) of all 1 s is not adequa te . If thi s is t he cas e, then e nte r the a ppropr iate I P broadcast address in dotted-decimal notation. If you set the IP Address parameter to 0.0.0.0 (to configure an unnumbered interface), Site Manager automatically sets this parameter to 255.255.255.255.

MIB Object ID: 1.3.6.1.4.1.18.3.5.3.2.1.4.1.8

Parameter: UnNumbered Assoc Address

Path: Select IP from the Select Protocols window and click on OK.

Default: None

Options: Any valid IP address

Function: Specifies an address that IP uses when sourcing a packet. RIP uses this address

to make decisions a bout adv ertis ing subnet s ov er th e unnumbered i nterfac e. RIP advertises subnets over the unnumbered interface if the subnets have the same mask as the associated address.

Instructions: Specify the address of any numbered interface on the router. If you are running

RIP over the unnumbered interface and if you are using a subnet address as the associated address, the local and remote associated addresses should have the same network number. If you configure local and remote associated addresses using different network numbers, you must use RIP2 mode.

MIB Object ID: 1.3.6.1.4.1.18.3.5.3.2.1.4.1.110

A-16

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AHB, BootP/DHCP, IP, and ATM Parameter Descriptions

ATM Interface Parameter Descriptions

Interface parameters define the state of the ATM interface. Figure A-7 shows the window sequence for the interface attributes category.

ATM

physical

interface

Upper layer

protocol

Service record

PVC

ATM

network

Site A

Site B

ATM0020A

Figure A-7. Interface Attributes Window Sequence

Parameter: Administrative State

Path: Configuration Manager > Protocols > ATM > Interfaces

Default: Up

Options: Up

Down

Function: Specifies whether this interface is enabled or disabled.

Instructions: Accept the default, Up, if you want traffic to flow over this interface. Set the

state to Down if you do not want traffic to flow over this interface.

MIB Object ID: 1.3.6.1.4.1.18.3.4.23.1.1.1.3

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A-17

Configuring ATM Half-Bridge Services

Parameter: Use Hardware MAC Address

Path: Configuration Manager > Protocols > ATM > Interfaces

Default: Enable

Options: Enable

Disable

Function: Specifies whether or not to use the hardware MAC address for this interface.

When this parameter is enabled, the Configuration Manager uses the ATM hardware MAC address of the link module for the end station identifier when automatically generating the user part (suffix) of an SVC service record ATM address.

When this parameter is disabled, the Configuration Manager uses the value specified in the MAC Address Override parameter to define the end station identifi er when auto matica lly gener ating th e user pa rt (suf f ix) of an SVC servi ce record ATM address.

Instructions: Accept the default, Enable, if you want to use the MAC address of the ATM

interface when automatically generating the end station identifier portion of the ATM address user part.

Set this parameter to Disable if you want to use the MAC Address Override value when automatically generating the end station identifier portion of the ATM address user part.

If you set this parameter to Disable, you must enter a value for the MAC Address Override parameter.

MIB Object ID: 1.3.6.1.4.1.18.3.4.23.1.1.1.18

A-18

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AHB, BootP/DHCP, IP, and ATM Parameter Descriptions

Parameter: Enable ATM Signaling

Path: Configuration Manager > Protocols > ATM > Interfaces

Default: Enable

Options: Enable

Function: Specifies whether ATM signaling is enabled or disabled for this interface.

Signaling allows you to configure switched features (for example, SVCs and LANE) on the interface.

If you do not intend to configure any switched features on this interface (that is, you want this interface to run only PVCs), disabling this parameter makes additional system resources available.

Instructions: Accept the default, Enable, if you want to enable signaling on this interface. Set

the state to Disable if you want to disable signaling on this interface.

MIB Object ID: 1.3.6.1.4.1.18.3.4.23.1.1.1.16

Disable

ATM Service Record Parameter Descript ions

Service record parameters define the ATM service records for an interface. The ATM Service Records List window also provides access to:

• Specific PVC parameters (PVC service records only)

• All SVCs on that service record (SVC service records only)

• LEC attributes (SVC service records using LANE data encapsulation)

Figure A-8

service attributes category and configure a PVC.

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shows the sequence of windows that can appear when you select the

A-19

Configuring ATM Half-Bridge Services

Configuration Manager

Edit ATM connector

Service attributes

Done

ATM service records

list window

window

ATM 1

window

Done

Add

PVC

ATM service record

parameters window

Cancel

A-20

ATM virtual channel

link window

Done

Add

ATM virtual channel

link parameters window

Cancel

Select protocols window

Figure A-8. Service Attributes Window Sequence (PVCs)

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Cancel

ATM0042A

AHB, BootP/DHCP, IP, and ATM Parameter Descriptions

Parameter: Enable/Disable

Path: Configuration Manager > Protocols > ATM > Service Records

Default: Enable

Options: Enable

Function: Enables or disables this service record.

Instructions: Accept the default, Enable, if you want traffic to flow on this service record and

its VCs. Set to Disable if you do not w ant traffic to flow on this service record or any of its VCs.

MIB Object ID: 1.3.6.1.4.1.18.3.4.23.1.2.1.2

Parameter: Data Encapsulation Type

Path: Configuration Manager > Protocols > ATM > Service Records > Add

Default: LANE (signaling enabled) or LLC/SNAP (signaling disabled)

Options: LANE

Function: Identifies the data encapsulation type for this service record.

You can use this parameter to select:

Disable

LLC/SNAP | NLPID | NULL

• LLC/SNAP, NLPID, or NULL data encapsulation for service records containing PVCs

• LLC/SNAP data encapsulation for service records containing hybrid PVCs

• LANE for service records containing SVCs over which you want to run LAN emulation

• LLC/SNAP or NULL for service records containing SVCs over which you want to run classical IP (RFC 1577)

If you select NULL, the router interprets this as virtual, channel-based multiplexing, which is not supported for bridging.

Instructions: Select a data encapsu la ti on type.

MIB Object ID: 1.3.6.1.4.1.18.3.4.23.1.2.1.5

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A-21

Configuring ATM Half-Bridge Services

Parameter: ATM Addr User Part

Path: Configuration Manager > Protocols > ATM > Service Records > Add

and Configuration Manager > Protocols > ATM > Service Records

Default: None

Options: 00000000000000 to FEFFFFFFFFFFFF

Function: The Configuration Manager allows you to autogenerate this parameter (see the

User Part Autogeneration parameter in Configuring ATM Services). Depending on the setting s in the ATM Interface Attributes window, this parameter can autogenerate this address using:

• The 6-byte hardware MAC address of the ATM interface

• A MAC Address Override value that you specify

In both cases, autogeneration creates a unique selector byte for each service record on the interface.

Instructions: Enter a value in the range specified.

MIB Object ID: 1.3.6.1.4.1.18.3.4.23.1.2.1.9

A-22

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AHB, BootP/DHCP, IP, and ATM Parameter Descriptions

ATM Virtual Channel Link Parameter Descriptions

Note:

ATM does not allow duplicate VPI/VCI pairs on the same physical interface. However, duplicate VPI/VCI pairs can exist on different physical interfaces.

Parameter: VPI Number

Path: Configuration Manager > Protocols > ATM > Service Records > PVC > Add

Default: None

Options: 0 to 255

Function: Identifies the virtual path of the PVC. The VPI is part of the cell header. The

header can contain a maximum of 8 VPI bits for a UNI connection. This bit range allows for path identifiers from 0 to 255.

Instructions: Enter a value from 0 to 255.

MIB Object ID: 1.3.6.1.4.1.18.3.4.23.1.5.1.3

Note:

identifiers from 0 to 31 are reserved for signaling and added functionality.

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Following the recommendation of the ATM Forum, virtual channel

A-23

Configuring ATM Half-Bridge Services

Parameter: VCI Number

Path: Configuration Manager > Protocols > ATM > Service Records > PVC > Add

Default: None

Options: 32 to 65535

Function: Identifies the v irtua l chann el of t he PVC. The VCI is part of the ce ll hea der. The

header can contain a maximum of 16 VCI bits. This bit range allows for path identifiers from 0 to 65535.

Instructions: Enter a value from 32 to 65535.

MIB Object ID: 1.3.6.1.4.1.18.3.4.23.1.5.1.4

Note: Following the recommendation of the ATM Forum, virtual channel

identifiers from 0 to 31 are reserved for signaling and added functionality.

Parameter: Hybrid/Bridged VC

Path: Configuration Manager > Protocols > ATM > Service Records > PVC

Default: No

Options: Yes

Function: Specifies whether the VC is set to hybrid access mode.

Instructions: Accept the default, No, if you want the VC to work in group access mode only.

Set to Yes if you want the VC to operate as a hybrid VC. For more informat ion about t he group and hybr id access mo des, see Confi guring

ATM Services.

MIB Object ID: 1.3.6.1.4.1.18.3.4.23.1.5.1.25

A-24

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This appendix provi des an overview of basic ATM concepts and the specific ways Nortel Networks implements these concepts on BayRS routers.

ATM General Information

Before you can begin using ATM Half-Bridge services, you must understand some basic ATM concepts and how ATM works.

Appendix B

Understanding ATM Concepts

Asynchronous Transfer Mode (ATM) is a connection-oriented, cell-based technology that relays traffic across a Broadband Integrated Services Digital Network (B-ISDN). It is a cost-effective way of transmitting voice, video, and data across a network.

ATM Cells

An ATM cell is a short, fixed-length packet of 53 bytes. It consists of a 5-byte header containing address information and a fixed, 48-byte information field.

Figure B-1

Cell Headers

After dividing the data into 48-byte segments for transmission, the end device (that is, the ATM DSU/CSU or native ATM device) attaches the required header information (Figure B-1

308611-14.00 Rev 00

shows a diagram of an ATM cell.

B-1

Configuring ATM Half-Bridge Services

5-byte

header

Bits

2345678

Generic flow control (GFC)

Virtual path identiﬁer (VPI) Virtual channel identiﬁer (VCI)

Virtual channel identiﬁer (VCI)

Header error control (HEC)

5-byte

header

48-byte

information field

Virtual path identiﬁer (VPI)

Payload type (PT)

48-byte

information ﬁeld

Cell loss

priority

Bytes

ATM0002A

Figure B-1. ATM Cell

B-2

ATM0001A

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Understanding ATM Concepts

The fields in each ATM cell header provide all the information necessary for networking. These fields include the following:

• Generic Flow Control (GFC): The first 4 bits of the cell header contain the

GFC. The GFC controls traffic flow onto the ATM network by controlling the user-network in terface (UNI).

• Virtual Path Identifier (VPI): The next 8 bits of the cell header (that is, the

last half of byte 1 and the first half of byte 2) contain the VPI. The VPI specifies a vir tua l pat h on the physical ATM link. See the next se ct ion , “ATM

Data Transmission,” for additional information on virtual paths.

• Virtual Channel Identif ier (VCI) : The ne xt 16 bi ts of t he cell he ader (t hat is,

the last half of byte 2, all of byte 3, and the first half of byte 4) contain the VCI. The VCI specifies a virtual channel within the virtual path on the physical ATM link. See the next section, “ATM Data Transmission

,” for

additional information on virtual channels.

• Payload Type (PT): The next 3 bits (that is, bits 5 to 7 of byte 4) indicate the

type of informat ion th e cell is carr ying (for exa mple, us er dat a or manag ement information).

• Cell Loss Priority (CLP): The last bit of byte 4 indicates the priority of the

cell and whether the network can discard it under heavy traffic conditions. Setting the bit to 1 i ndicat es that the net w ork may dis card th e cel l if ne cessa ry.

• Header Error Control (HEC): The last byte of the header field contains the

HEC. Its primary function is to guard against misdelivery of cells due to header or single bit errors. However, the HEC does not gauge the quality of the data in the information field.

ATM Data Transmission

Data transmission (also called cell switching) through the ATM network relies on the establishment of logical conne ctions betw een ATM en tities. ATM is a connection-oriented service. Th is means that an ATM entity cannot transmit information until it establishes a connection with a receiving entity. These connections consist of virtual channels, virtual paths, and transmission paths.

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B-3

Configuring ATM Half-Bridge Services

A virtual channel is a logical connection between two communicating ATM entities. Each virtual channel may carry a different protocol or traffic type. The virtual channel transports cells that have a common identifier. The identifier is called the virtual channel identifier (VCI) and is part of the cell header. You can establish virtual channels permanently or set them up dynamically, allowing the network to adjust itself to the traffic demand.

A virtual path is a set of virtual channels between a common source and destination. The virtual channels in a virtual path logically associate with a common iden tifier. This identifier is called the virtual path identifier (VPI) and is part of the cell header. You can base cell switching on either th e VPI alone or on a combination of the VPI and VCI.

V irt ual paths en able you t o separa te networ k trans por t funct ions in to thos e relat ed to an individual logical connection (virtual channel) and those related to a group of logical connections (virtual path).

A transmission path is a physical connection that comprises several virtual paths, each virtual path containing several virtual ch annels. The transmission pa th may support multiple virtual paths across a single connection to the network.

B-4

Figure B-2

shows the relationships between the virtual channel, the virtual path,

and the transmission path.

Transmission Path

Figure B-2. ATM Transmission Components

VP VP

VP = Virtual path VC = Virtual channel

VP VP

ATM0006A

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Permanent Virtual Connections

Virtual channels and virtual paths allow you to establish virtual channel links (VCLs). To use the ATM Half-Bridge protocol, you must create VCLs as permanent virtual circuits (PVCs). Once you establish a PVC, you can transfer information over it at any time.

Service Records and Virtual Circuits

ATM devices communicate using virtual circuits (VCs). These VCs transmit and receive ATM cells containing upper-layer protocols. Nortel Networks ATM routers use service records to provide a way of creating logical interfaces (within the physical ATM interface) for these upper-layer protocols. In essence, these service records allow you to:

• Organize multiple VCs into logical groups.

• Create direct, point-to-point connections.

• Assign, delete, and modify upper-layer protocols for just one PVC, or for a

group of VCs, at any given time.

Understanding ATM Concepts

Data Encapsu lat ion

Nortel Networks ATM routers support multiprotocol encapsulation (as defined in RFC 1483), enabling the ro uter to mul tiple x (combine) and demulti ple x (separa te) bridged or routed protocol data units (PDUs).

For transmission, the encapsulation process adds a header between 2 and 8 octets in length to the PDU to allow decoding. The decoding process determines the proper service access point (SAP).

When receiving information, the encapsulation method evaluates the header to determine whether the PDU is a valid routed or bridged cell. If it is valid, the encapsulation method then strips the header from the cell and passes it to the appropriate SAP for routing or bridging.

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B-5

Configuring ATM Half-Bridge Services

Assigning a Data Encapsulation Type for a PVC

With AHB, you must assign the Logical Link Control/Subnetwork Access Protocol (LLC/SNAP; RFC 1294) to the PVC that you create. LLC/SNAP encapsulation attaches an LLC/SNAP header before the PDU. This header includes information that the receiver needs to properly process the incoming PDU.

When assigning a data encapsulation type to a PVC or group of PVCs, keep the following in mind:

• The Site Manager ATM Service Records List and ATM Virtual Channel Link

windows initially contain a default data encapsulation type of LLC/SNAP.

• When you add a PVC, it reads and uses the data encapsulation type specified

in its ATM service record.

• You can globally assign a data encapsulation type to all nonhybrid PVCs in a

particular service record, or you can assign a data encapsulation type to individual group PVCs using the Site Manager ATM Virtual Channel Link window.

Caution:

changes the data encapsulation type for all nonhybrid PVCs on that service record. For e xa mple, if you chan ge the ATM serv ice re cord dat a encaps ulati on type from LLC/SNAP to NULL, the data encapsulation type for all PVCs (except hybrid P VCs) on that se rvice record changes to NUL L. Site Manager does not ask you to verify this change.

• If you change the data encapsulation value in the Site Manager ATM Service

Changing the data encapsulation type at the service record level

Records List windo w, all new PVCs that you add t o that servic e record us e the new value.

PVC Access Methods

For AHB, you can set up PVCs to access an ATM network in the following ways:

• Multiple PVCs per sevice record

• One PV C per service record

B-6

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Multiple PVCs

Of the two methods, having multiple PVCs per service record uses network addressing most efficiently and is the easiest to configure.

Upper-layer pro tocols treat each servic e re cord on an ATM network interf ac e as a single access point . These protocols use a single networ k address to send al l traf f ic destined for the network to the ATM network interface. Figure B-3 conceptual drawing of multiple PVCs accessing an ATM network through one service record.

Upper-layer protocol

ATM

physical

interface

Service record

PVC PVC PVC

PVC PVC

Understanding ATM Concepts

shows a

Site A

ATM

network

Site B

Site C

Site D

Site E

Figure B-3. Multiple PVCs per Service Record

Although you need to configure each PVC manually, you need only defi ne and associate protocols with the ATM network service record. All the PVCs that you configure for a given ATM service record carry the protocols that you select and configure to run on that service record.

Note:

the data encapsulat ion type that you set for the ATM service reco rd (that is , the value of the Data Encapsulation Type parameter set in the ATM Service Records List window). Refe r to “Data Encapsulation,” earlier in this chapter, for more information.

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ATM0018B

When you configure multipl e PVCs per service recor d, the PVCs all use

B-7

Configuring ATM Half-Bridge Services

Multiple PVCs per service record wor k best in either fully meshe d environments or in nonmeshed en viro nments where syste ms not direct ly connected to eac h other have no need to communicate. You can configure multiple PVCs per service record as long as you do not need to separate protocols by PVC (that is, all PVCs accept the same protocols).

There are, howe v er , ways t o conf igure upper -layer p rotocols, suc h as IP or Interne t Packet Exchange (IPX), to allow systems in nonmeshed networks to fully communicate. See the documentation for these upper-layer protocols for more information.

One PVC

One PVC per service record works the same way as multiple PVCs per service record, except that you assign only one PVC per service record.

This type of configu rati on is best suited to small, nonme shed configurations, or to configuratio ns in which proto cols must resid e on separate PVCs. When you de fine only one PVC per service record, uppe r-layer protocols treat t he ATM networ k as a series of direct, point-to-point connections, viewing each PVC as an individual network interface.

B-8

You can, therefore, configure each PVC with different protocols and parameter settings. This allows you to connect to different network sites using, for example, different types of data encapsulation (Figure B-4

308611-14.00 Rev 00

Understanding ATM Concepts

ATM

physical

interface

Upper layer

protocol

Service record

PVC

ATM

network

Site A

Site B

ATM0020A

Figure B-4. One PVC per Service Record

Assigning one PVC per service record allows you to dedicate a PVC to a particular protocol, but at the expense of some configuration ove rhead, memory, and address space.

Note:

The maximum number of PVCs you can configure in this way varies, depending on the configuration of the router, the number of protocols running on the circuits, and the number of routing entries.

308611-14.00 Rev 00

B-9

acronyms, xv adding

ATM circuit, 2-6 ATM to the router, 2-9 PVCs, 2-9 service records

PVC, 2-7

Administrative State

parameter description, A-17

ADSL terminal unit

central devices (ATU-C), 1-2

remote end devices (ATU-R), 1-2 Alternate Init File parameter, 3-5, A-4 ARP requests, 1-9 ATM, 1- 3

cell

described, B-1 switching, B-3

technology, B-1 circuit, adding, 2- 6 concepts, B-1 to B-5 data transmission, B-3 transmission path, defined, B-4 virtual channel, defined, B-4 virtual path, defined, B-4

ATM Addr User Part

parameter description, A-22

ATM Half-Bridge (AHB)

auto learning methods

both, 1-3

none, 1-3

secure, 1-3

unsecure, 1-3

Index

bridge entries

adding, 1-9 deleting, 1-9

removing, 1-9 concepts and terminology, 1-1 configuration, 2-5 configuration requirements, 2-1 described, 1-1 forwarding inbound packets, 1-4 maintaining the bridge table for, 1-3 modifying the AHB configuration, 3-1 network planning considerations, 2-1 responding to ARP requests, 1-9 starting, 2-1 using inbound packet filtering, 1-12 using source-based routing, 1-9

Auto Learn Method parameter , 3-2, A-3

BootP

configuring preferred servers, 2-12 defining forwarding pat hs, 2-10

Broadband Integrated Services Digital Network

(B-ISDN), B-1

cell

switching, B-3 technology, B-1

circuitless IP interface

configuring, 2-4

Configuration, A-6, A-19, A-22 conventions, text, xiv customer support, xvii

308611-14.00 Rev 00

Index-1

Data Encapsulatio n Type

parameter description

service record, A-21 Debug Level parameter, 3-6, A-4 DHCP

defining forwarding pat hs, 2-10

using to dynamically assign IP addresses, 1-3 digital subscriber line (DSL), 1-1 DSL access multiplexor (DSLAM), 1-2

Enable ATM Signaling

parameter description, A-19 Enable parameter, A-3, A-6 Enable Proxy ARP parameter, 3-10, A-7 Enable/Disable (service record)

parameter description, A-21 encapsulation, multiprotocol, B-5

forwarding paths, BootP and DHCP, 2-10

Hops parameter, A-9 Hybrid/Bridged VC

parameter description, A-24

inbound packet filteri ng, 1-12 Inbound Packet Filtering parameter, A-5 Init File parameter, 3-3 Input IP Address parameter, A-11 interface

parameters

Administrative State, A-17 Enable ATM Signaling, A-19 Use Hardware MAC Address, A-18

window sequence, A-17

Interface attributes

selecting, A-17 window sequence, A-17

starting, 2-3

IP Address parameter, A-15

IP configuration, 2-8, A-15

Learned Host Subnet Mask parameter, A-7 LLC/SNAP

defined, B-6 LLC/SNAP service record, 2-7 Local Init File parameter, A-4

multiprotocol encapsulation, support, B-5

Output IP address parameter, A-12

parameters

customizing, 3-1 parameters. See individual parameter names, 3-1 Pass Through Mode para meter, A-10 product support, xvii protocols

editing, 2-7

editing for hybrid access (nonbridging), 2-7

enabling for

hybrid access (nonbridging ), 2 -7

service record, 2-7 publications

hard copy, xvii PVCs, 2-5

adding, 2-9

and service records, B-5

multiple per service record, B-7

one per service record, B-8

Index-2

308611-14.00 Rev 00

parameters

Hybrid/Bridged VC, A-24 VCI Number, A-24 VPI Number, A-23

Relay Agent IP Address parameter, A-14 requirements, 3-1 RFC 1483 encapsulation, 1-2

secure learning method, 1-8 service attributes

descriptions, A-19 window sequence (PVC), A-20

service records

adding (PVC), 2-7 data encapsulation types for, 2-6 defined, B-5 parameters

ATM Addr User Part, A-22 Data Encapsulatio n Type, A-21 Enable/Disable, A-21

window sequence (PVCs), A-20 source-base d r ou tin g, 1- 9 starting

IP, 2-3

IP on circuitless interface, 2-4 Subnet Mask parameter, A-15

IP configuration, 2-3, A-15 support, Nortel Networks, xvii SVCs

and service records, B-5

transmission path, defined , B-4 Transmit Bcast Addr parameter, A-16

IP configuration, 2-3, A-16

UnNumbered Assoc Address parameter, A-16

IP configuration, 2-3, A-16 unsecure learning method, 1-8 Use Hardware MAC Address

parameter description, A-18

VCI Number

parameter description, A-24 virtual channel identifier (VCI), defined, B-4 virtual channel, defined, B-4 virtual circuits. See PVCs or SVCs virtual path identifier (VPI), defined, B-4 virtual path , defined, B-4 VPI Number

parameter description, A-23

Target Name parameter, A-13 Target Server IP Address parameter, A-15 technical publications, xvii technical support, xvii text conventions, xiv Timeout Secs. parameter, A-9

308611-14.00 Rev 00

Index-3

Avaya ATM Half-Bridge User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Configuring ATM Half-Bridge Services

Contents

Figures

Tables

Before You Begi n

Preface

Text Con ventions

Acronyms

Hard-Copy Technical Manuals

How to Get Help

What Is ATM Half Bridge?

How the AHB Router W orks

Forwarding Inbound Packets from CPE Hosts

Forwarding Outbound Packets to CPE Hosts

Using DHCP to Dynamically Assign IP Addresses

Dynamically Learning New Bridge Table Entries

Unsecure Learning Method

Secure Learning Method

Maintaining the AHB Bridge Table

Adding Bridge Table Entries

Removing Bridge Table Entries

Replacing Bridge Table Entries

Using Source-Based Routing

Responding to Proxy ARP Requests

Using Inbound Packet Filtering

Network Planning Considerations

AHB Configuration Requirements

Preparing a Configuration File

Configuring an IP Interface on the Router

Configuring Circuitless IP on the Router

Configuring AHB Services

Creating an ATM Interface

Adding an LLC/SNAP PVC Service Record

Adding AHB to the LLC/SNAP Service Record

Adding PVCs to the LLC/SNAP PVC Service Record

Configuring a DHCP/BootP Relay Agent

Creating a BootP Relay Agent Forwarding Interfaces

Configuring BootP Preferred Servers

Specifying the Relay Agent IP Address

Specifying the Target Server IP Address

Modifying the AHB Configura tion

Enabling and Disabling AHB

Setting the Auto Learn Method

Configuring a Local AHB Init File

Sample Init File

Specifying an Alternate Init File

Specifying the Debug Level

Enabling and Disabling Inbound Packet Filtering

Modifying AH B Circuit s

Enabling and Disabling an AHB Circuit

Specifying the Subnet Mask for the Learned Host

Enabling and Disabling Proxy ARP on a Circuit

Configuring Traffic Filters for Source-Based Routing

Deleting AHB from the Router

AHB Global Parameters

AHB Circuit Para meters

BootP Relay Agent Interface Table Parameters

BootP Address Parameters

BootP Relay Agent Preferred Server Table Parameters

BootP Preferred Server Configuration Parameters

IP Configuration Parameters

ATM Interface Parameter Descriptions

ATM Service Record Parameter Descript ions

ATM Virtual Channel Link Parameter Descriptions

ATM General Information

ATM Cells

Cell Headers

ATM Data Transmission

Permanent Virtual Connections

Service Records and Virtual Circuits

Data Encapsu lat ion

Assigning a Data Encapsulation Type for a PVC

PVC Access Methods

Multiple PVCs

One PVC

Index