EXP Computer PathBuilder S200 User Manual
3Com
®
Corporation
PathBuilder™ S200 Series Switch
Bridging
Notice
©
1998 3Com Corporation
5400 Bayfront Plaza
Santa Clara, CA 95052-8145
(408) 326-5000
All rights reserved.
Printed in U.S.A.
Portions reprinted with the permission of Motorola, Inc.
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®
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Information and software in this document are proprietary to 3C om (or its Suppliers) and
without the express prior permission of an officer of 3Com, may not be copied, reproduced,
disclosed to others, publi shed, or used, in whol e or in part , for any purpos e other t han that for
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This document is for information purposes only and is subject to change without notice.
Part No. T0008-16, Rev. F
First Printing October 1998
Manual is current for Release 5.2M.
Bridging
Overview
Functionality PathBuilder S200 serie s swit ches su pport b ridgi ng of dat a traf f ic for Ethern et LANs.
Bridging LAN traffic minimizes your networking costs by eliminating the need for
redundant networks and maximizes the availability of dedicated facilities such as
servers and printers, as well as public Frame Relay and X.25 services, across
multiple LANs.
Remote Bridging
Solutions
PathBuilder S200 series switches are intended for use in remote bridging solutions.
This means the PathBuilder S200 series sw itch is best used t o connect a re mote LAN
to the WAN to connect to other remot e LANs in you r networ k, as sh own in Fig ure 1.
Ethernet
PB S200
Token
Ring
PB S200
PB S200
X.25/FR
PB S200
Token
Ring
Ethernet
Figure 1. PathBuilder S200 Series Switch Bridge Combining Traffic
from Serial Devices
Figure 1 shows PathBuilder S200 series switches acting as remote bridges to
combine data traffic from Ethernet LANs to the WAN to connect to other remote
LANs in the network.
Bridging 1
Mixed LAN Support PathBuilder S200 series switches support mixed LAN bridging, meaning you can
configure an Ethernet interface in the same node. Refer to the “Mixed LAN
Bridging” section on page 8 for more details.
Translational
Bridging
PathBuilder S200 series switches can use the Translational Bridging feature to
bridge traffic between Ethernet Networks. Translational Bridging provides a
PathBuilder S200 series switch with the capability to bridge non-routable protocols.
For information about enabling and configuring Translational Bridging, refer to the
“Configuring Translational Bridging” section on page 37.
No Local Bridging As mentioned earlier, PathBuilder S200 series switches are not intended for use in
local bridging applications where one LAN is connected directly to another LAN. It
is not recommended you use PathBuilder S200 series switches to perform local
bridging.
Transparent
Bridging
Transparent Bridging (TB) is the method used by PathBuilder S200 series switches
to bridge Ethernet LAN traffic from one Ethernet LAN to another one across a
WAN.
Refer to Transparent Bridging for Ethernet LANs on page 48 for more details on
these bridging operations.
Supported T raffic The PathBuilder S200 series switch family supports many types of protocols for
bridging operations. Some of the supported protocols include:
•Async
•SDLC
• Bisync
• Transparent Polled Async
• HDLC
• X.25
• Frame Relay
• Burroughs Poll Select
• NCR Bisync
2 Bridging
In This Manual Topic See Page
Bridging Features and Capabilities .............................................................. 5
Token Ring LAN ...................................................................................... 6
Ethernet LAN ........................................................................................... 8
Mixed LAN Bridging ............................................................................... 10
MAC Addressing ..................................................................................... 11
LLC2 Local Termination ................................................................. ......... 12
Autolearn for Local Termination .............................................................. 13
Filtering .................................................................................................... 14
Spanning Tree Protocol ............................................................................ 15
Dual Ethernet LANs ................................................................................. 16
Basic Remote Bridging Examples ................................................................ 17
Bridge Hardware Components in PathBuilder S200 Series Switches .......... 19
Setting Up WAN Operation for Bridging ..................................................... 20
Configuring the PathBuilder S200 Series Switch for Bridging Operation ... 22
Bridge Parameters .................................................................................... 23
Bridge Link Parameters ............................................................................ 27
LAN Connection Table ............................................................................ 32
Limiting Bridge Frame Sizes ................................................................... 36
Configuring Translational Bridging ......................................................... 38
Source Route Bridging for Token Ring LANs ............................................. 40
Bridge Frame Handling ............................................................................ 41
Source Route Bridging Operation ............................................................ 42
Configuring Source Route Bridging Operation ....................................... 45
Connecting a Station to a Server in Source Route Bridging .................... 47
Transparent Bridging for Ethernet LANs ..................................................... 53
Forwarder Database and Spanning Tree .................................................. 58
Using Filters ............................................................................................. 59
Transparent Bridge Configuration Parameters ......................................... 61
Bridge Filtering ............................................................................................ 62
MAC Address Filtering ............................................................................ 63
MAC Address Filtering Examples ........................................................... 67
Identifying Address Links for MAC Addressing ..................................... 72
MAC Wildcard Filtering .......................................................................... 73
Configuring the MAC Address Filter Table ............................................. 74
Protocol Filtering ..................................................................................... 78
Configuring the Protocol Filter Table ...................................................... 79
NetBIOS Name Filtering .......................................................................... 84
Configuring NetBIOS Name Filtering ..................................................... 86
NetBIOS Name Filtering Statistics .......................................................... 92
NetBIOS Packet Formats . ........................................................................ 93
Spanning Tree Protocol Entity (STPE) ......................................................... 94
STPE Parameter Setting Considerations ......................................... ......... 97
Spanning Tree Timers .............................................................................. 103
Bridge Forward Delay Timer ................................................................... 105
LLC2 Local Termination .............................................................................. 108
Configuring Local Termination ................................................................ 114
Deleting LT Configuration Records ......................................................... 121
Mixed LAN Operation ................................................................................. 122
Dual LAN Ethernet ....................................................................................... 125
LAN Server Subsystem ................................................................................ 128
Configuring the LSS Record .................................................................... 130
Bridging 3
T0008-16F Release 5.2M
In This Notice
(continued)
Topic See Page
Bridge Statistics ............................................................................................ 132
Spanning Tree St atistics ........................................................................... 133
Detailed Bridge Link Statistics ................................................................ 135
Bridge Link Filter Summary .................................................................... 138
Transparent Bridge Forwarding Table Statistics ...................................... 140
Transparent Bridge Detailed Bridge Link St atistics ................................. 142
LAN Connection Statistics ....................................................................... 144
LLC2 LT Session Summary Statistics ...................................................... 149
LLC2 LT Detailed Session Statistics ........................................................ 151
Reset Statistics .......................................................................................... 155
4 Bridging
Bridging Features and Capabilities
Bridging Features and Capabilities
Introduction This section describes bridging features and capabilities of PathBuilder S200 series
switches.
Bridging Primer As mentioned earlier, Bridging extends the size and coverage of a Local Area
Network (LAN). PathBuilder S200 series switches provide bridging support for up
to two 802.3 (Ethernet) LAN interfaces per node or one 802.5 (Token Ring) LAN
interface) per node, and up to 32 remote bridge connections.
A PathBuilder S200 series switch b ridge can be connected t o a WAN backbone made
up of X.25, Frame Relay, or both, as shown in Figure 2.
Token
Ring
PB S200
FR/X.25
PB S200
Figure 2. Example of Typical PathBuilder S200 Series Switch Bridging
Application
PathBuilder S200 series switches are best suited for remote bridging operations
where traffic flows from one LAN through a WAN bridged by at least two
PathBuilder S200 series switches to another LAN.
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Bridging Features and Capabilities
Ethernet LAN
What Is It? Ethernet is a common implementation of LAN topology wherein stations are
connected using a bus topology. Stations access the Ethernet using Carrier Sense
with Multiple Access and Collision Dete ction (CSMA/CD ).
PathBuilder S200
Series Switch
Support for
Ethernet
Example of Basic
Ethernet Frame
Format
PathBuilder S200 seri es switch Ethernet f unct io nal it y c omplies with the IEEE 802.3
specifications and provides Transparent Bridging to transport many different
protocols over the Wide Area Network (WAN) to remote destinations. Supported
protocols include:
• Novell Netware
•DECnet
• Banyan Vines
Figure 3 shows the basic frame formats for Ethernet frames supported by
PathBuilder S200 series switches.
Ethernet Frame Format
Preamble
8Octets
Destination Source Type
662445-1500
64-1518
Data
FCS
Figure 3. Frame Format for Ethernet Frames
802.3 MAC Frame
Figure 4 shows the supported 802.3 Ethernet MAC Frame format.
Format
802.3 MAC Frame Format
Preamble
SFD Destination Source Len Data Unit Pad FCS
DSAP SSAP Control Higher Layer Information
1 1 1 or 2
802.3.LLC
42-1497
Octets
Figure 4. 802.3 Ethernet MAC Frame Format Example
6 Bridging
Bridging Features and Capabilities
Example of
Ethernet Bridge
Operation
Figure 5 shows an example of two Ethernet LANs connected across a WAN using
two PathBuilder S200 serie s switc hes as br idges . The ex ample sho ws a Frame Rel ay
WAN application, but you can also bridge across an X.25 WAN.
Frame Relay
PB S200PB S200
Figure 5. Ethernet Bridge Example
For More Details... For more details on bridging Ethernet LAN traffic, see Transparent Bridging for
Ethernet LANs on page 48.
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Bridging Features and Capabilities
Mixed LAN Bridging
What is It? PathBuilder S24x, 26x, and 27x switches support a mixture of Token Ring and
Ethernet interfaces configured in the same node. This means the PathBuilder S24x,
26x, and 27x switch is able to perform remote Transparent bridging for Ethernet
LANs from the same PathBuilder S24 x, 26x, and 27x swit ch as shown in Fi gure 6. If
you happen to configure two Ether net LAN inter fa ces in the same node, instead of a
mix of one Ethernet and one Token Ring, you can perform local Transparent
bridging between the two Ethernet LANs.
Ethernet 1
Ethernet 2
Port 13
Port 19
PB S200
WAN
PB S200
Ethernet 1
Ethernet 2
Figure 6. Example of Mixed LAN Bridging in PathBuilder S24x, 26x, and
27x Switch
Note
Mixed LAN operation does not support translational bridging, meaning you
cannot pass LAN traffic from an Ethernet LAN to a Token Ring LAN without
using some sort of conversion software.
For More Details Refer to the “Mixed LAN Operation” section on page 114 for more details.
8 Bridging
Bridging Features and Capabilities
MAC Addressing
What Is It? Bridges, whether they using Transparent Bridging, operate at the Data Link Layer,
which is concerned with MAC addressing. The MAC Address is a 6-byte MAC
(Media Access Control) address that identifies stations on a LAN. The IEEE
administers distribution of the MAC address to ensure no duplicates occur in MAC
addressing. This is accomplished by assigning a unique MAC address to each
manufacturer. Each manufacturer then assigns sequential values to the lower three
bytes for each interface manufactured.
For More Details For more details on MAC Address filtering, see the section “MAC Address
Filtering” section on page 58”in this manual.
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Bridging Features and Capabilities
LLC2 Local Termination
LLC2 Local
Termination
PathBuilder S200 series switch support includes LLC2 Local Termination for your
Bridging operations when pas sing SNA/SDLC data tra f fic. LLC2 Local Termination
lets specific Token Ring ports generate and respond to LLC2 polls with local
acknowledgments, thereby preserving bandwidth and preventing session timeouts.
Local Termination, also referred to as “spoofing,” provides an efficient means for
carrying out an LLC2 session between two SNA end stations attached to separate
Token Ring LANs connected by a Wide Area Network (WAN).
Additionally, Local Termination provides detailed statistics on LLC2 sessions.
LT Example Figure 7 shows a network where running LLC2 Local Termination at the edge point
PathBuilder S200 series switches enables spoofing from one side of the network to
the other across multiple Token Rings.
SNA
FEP
LLC2
Keepalives/Acks
Keepalives/Acks
Keepalives/Acks
LLC2
LLC2
LLC2
Keepalives/Acks
LLC2
Keepalives/Acks
CC
CC
Figure 7. Local Termination Example
For More Details... See“LLC2 Local Termination” section on page 100 in this guide.
10 Bridging
Bridging Features and Capabilities
Autolearn for Local T ermination
What Is It? Local Termination Autolearn reduces the amount of configura tion you need to do by
letting you spoof remote sessions without configuring a MAC address and a Service
Access Point (SAP) for each station running a session to the host Front End
Processor (FEP).
Since Local Termination supports up to 256 sessions for the PathBuilder S24x, 26x,
and 27x switch, Local Termination Autolearn can save you consid erabl e time duri ng
the configuration process.
Local Termination Autolearn is a default feature with PathBuilder S200 series
switches operating software meaning it requires no special configuration, other than
configuring the remote host MAC address in the PathBuilder S200 series switch
Local Termination (LT) Station tables.
It does not interfere with previously configured Local Termination spoofing
sessions.
Example Figure 8 shows how a PathBuilder S200 series switch automatically learns the
address of PCs connected to the local bridge so you can pass data traffic to the host
without configuring entries in the Local Termination Station table for each PC
session.
1
The PC’s destination MAC address must match the
MAC address configured in the remote Host FEP for
local PB S200 to automatically learn LAN MAC
addresses.
Configure the Host FEP MAC address and SAP in the
2
LT station tables of the local an d remote bridges.
PB S200 automatically learns MAC addresses of any
LAN devices with matching desti na ti on MAC
addresses.
The local PB S200 running Local
3
Termination Autolear n automatically
learns MAC addresses of stations on
Destination MAC
addresses set up
40:00:00:00:10:88
local LAN.
Figure 8. Example of Local Termination Autolearn
PB S200
PB S200
Host MAC
address:
40:00:00;00:10:88
FEP
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Bridging Features and Capabilities
Filtering
What Is It? Filtering lets you restrict data traffic from certain segments of your network. There
are different methods used to filter data traffic on a bridged network. PathBuilder
S200 series switch support for filtering includes:
• MAC Address Filtering
• NetBIOS Name Filtering
• Protocol Filtering
Mac Address
Filtering
NetBIOS Name
Filtering
MAC Addressing is important in a bridging operation because one of the most
common tasks in a bridging environment is to provide filtering of data frames.
Filtering provides a way of stopping certain d evi ce s f rom c ommunicating with other
devices in a network. One way to filter traffic through a bridge is by identifying the
devices you want to block by their MAC Addresses.
For more details on MAC Address filtering, see the section “MAC Address
Filtering” section on page 58” in this manual.
The NetBIO S Name Filtering feature of PathBuilder S200 serie s switches le ts you
restrict or filter all NetBIOS broadcasts, except those to or from a list of servers.
NetBIOS Name Filtering compares NetBIOS broadcasts to a “pattern” that may have
a wild card “*” character at the end. For example, if all servers have a naming
convention with the fir st pa rt of t he name the same, for example, “SVR...”, then you
can complete only one ent ry i n t he Ne tBIOS Filter Table to permit broadcasts to and
from the “SVR*” name pattern.
With NetBIOS Name Filters, you can block the local service name (for example,
“SNA_GW”) on the WAN link so that NetBIOS broadcasts to and from that name
are not forwarded across to the internetwork.This feature lets the branches use the
same name for their loc al SNA ser vi ce a nd you can configure all th e workstations to
access the same local SNA name.
Refer to “NetBIOS Name Filtering” section on page 76 in this guide.
Protocol Filtering Protocol filtering prevents nodes operating with a certain protocol from operating
outside their intended scope.
Refer to the“Protocol Filtering” section on pag e 70 for more details.
12 Bridging
Bridging Features and Capabilities
Spanning T ree Protocol
What Is It? Spanning Tree Protocol reduces multiple bridge paths between LANs to a single
path. Instead of a mesh network with several paths to a destination, the Spanning
Tree Protocol remaps the network so that only one path is active for traffic between
any source station and any destination station. The other paths block any frames
between the LANs.
A spanning tree network eliminates parallel paths and traffic loops.
The PathBuilder S200 series switch implementation of the Spanning Tree Protocol
Entity (SPTE) conforms to IEEE 802.ID specifications. Refer to the IEEE 802.ID
specification for more detailed information on Spanning Tree Protocol operation.
Automatic &
Manual Spanning
Tree Support
PathBuilder S200 series switch support both automatic and manual spanning tree
operations.
If you do not want to configure spanning tree operation yourself, you can use the
automatic spanning tree creation option. Remember that a all bridges in your
network must be configured to automatic spanning tree operation to allow for the
spanning tree protocol to determine the spanning tree.
For More Details... See the“Spanning Tree Protocol Entity (STPE)” section on page 86.
Bridging 13
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Bridging Features and Capabilities
Dual Ethernet LANs
What Is It? The PathBuilder S24x, 26x, and 27x switch supp orts up to two Ethernet LANs in t he
same node. This means you can connect up to two Ethernet LANs to a single
PathBuilder S24x, 26x, and 27x switch to perform bridging and routing of LAN
traffic across the WAN to multiple Ethernet LANs. Before Dual Ethernet LAN, the
PathBuilder S24x, 26x, and 27x switch supported only one Ethernet LAN port for
remote bridging and routing of LAN traffic.
For More Details... See the “Dual LAN Ethernet” section on page 117.
14 Bridging
Basic Remote Bridging Examples
Basic Remote Bridging Examples
Introduction This section shows some common examples of bridging applications using
PathBuilder S200 series switches.
Remote Bridging
Across a WAN
Extended Bridging
for Multiple LANs
Figure 9 shows a common Source Route Bridging operation for PathBuilder S200
series switches where two Token Ring LANs are attached across a WAN. For
example, two LANs could be bridged using two PathBuilder S200 series switches
interconnected by an X.25 or Frame Relay link. Bridged traffic flows between the
bridges over a Swit ched Virtual Circuit (SVC) tha t conne cts them t ogether a cross th e
WAN (or Permanent Virtual Circuit (PVC) for Frame Relay).
Token
Ring 1
PBS200
Node 1
X.25/Frame Relay
PBS200
Node 2
Token
Ring 2
Figure 9. PB S200s Connecting LANs via an X.25/Frame Relay Link
If more than two remote LANs are involved in your bridging application, the bridge
arrangement can be e xtended s o that individua l LAN pair s are co nnected by di ff erent
bridges, as shown in Figure 10.
Token
Ring 1
Node 1
Bridge 1
Bridge 2
Node 2
Bridge 1
Bridge 3
Token
Ring 2
Token
Ring 3
Node 3
Bridge 2
Bridge 3
SVC Connectors
(PVC for Frame Relay)
Figure 10. Two-Port Bridges Connecti ng Mult ipl e Token Ring LANs
In this example, each pair of LANs is connect ed by a sing le bridge fo rmed by bridge
pairs.
• Bridge 1 interconnects Token Ring 1 and Token Ring 2
• Bridge 2 interconnects Token Ring 1 and Token Ring 3
• Bridge 3 interconnects Token Ring 2 and Token Ring 3
Bridging 15
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Basic Remote Bridging Examples
A Less Complex
Extended Bridge
Figure 11 shows a possible arrangement of SVCs (PVCs for Frame Relay) that
produces the same bridge arrangement as shown in Figure 10.
Token
Ring 1
Token
Ring 3
Node 1
Bridge 1
Bridge 2
SVC Connectors
Node 3
Bridge 2
Bridge 3
Node 2
Bridge 1
Bridge 3
Token
Ring 2
Figure 11. Example of Bridges in an SVC Arrangement
In this arrangement, all LAN segments are one hop away from each other since they
are directly attached by a single pair of bridges. In Figure 11, Token Ring 1 is one
bridge away from Token Ring 2 and Tok en Ring 3 and the same applies for the othe r
rings.
From a bridged netw or k po int of view, Token Ri ng 1 i s one bridge away fr om Token
Ring 3, but Node 1 is not directly connected to Node 3. Traffic between Token Ring
1 and T oke n Ring 3 does n ot have to pass th rough Token Ring 2. This is an important
advantage in configuring bridge networks with the PathBuilder S200 series switch
because you can form a minimal bridge network to accomplish the desired
interconnectivity.
16 Bridging
Bridge Hardware Components in PathBuilder S200 Series Switches
Bridge Hardware Components in PathBuilder S200 Series Switches
Introduction This section describes bridge hardware configuration and connections for the
PathBuilder S200 series switch.
Bridge
Configuration and
Connections
Figure 12 shows the physical connections of the modules that provide bridging
functiona lity for PathBuilder S200 series switch . This figure shows a LAN port
module and supporting WAN Adapter module within a PathBuilder S200 series
switch. The LAN port module is br oken out int o a driver and a forwarder to show the
concept of bridge links.
At each end node, the bridge has connectio ns referr ed to as brid ge links. Bridge links
that connect to the LAN are referred to as LAN bridge links. Bridge links that
connect to remote bridges across the WAN are referred to as WAN bridge links.
LAN Link Numbers range from 1 to
4: up to two LAN connections are
supported for Ethernet.
LAN Port Module
Token
Ring
LAN
LAN
Driver
1
Forwarder
LAN
Bridge
5
.
.
.
.
32
Up to 32 WAN links can be defined
(numbered 5 to 36), o ne f or each
bridge connection over an SVC
(PVC for Frame Relay).
WAN
Adaptor
X.25 SVCs connected to
SVCs on network ports
(PVCs for Frame Relay)
Figure 12. LAN Port Module and WAN Adapter Module (Logical View)
The LAN port consists of low level drivers and the bridge forwarder. This can be
viewed as the functioning bridge. The WAN Adapter is closely associated with the
bridge. The WAN Adapter provides the network services that the bridge requires in
order to function over the WAN network. The principal service is establishing and
maintaining S VC (PVC for Frame Relay) connections to remote LAN bridge
forwarders so that virtual circuits can be formed betwee n the forwarders.
The bridge sees the LAN and th e WAN (by means o f the WAN Adapter) as networ ks
it is attached to by links. There are a total of 36 links: four LAN links and 32 WAN
links.
LAN Interface
Support
The PathBuilder S200 series switch supports only one LAN per node, so only one
link is needed for the LAN port connection: link number 1. The PathBuilder S24x,
26x, and 27x switch supports up to two Ethernet LANs per node. See “Dual LAN
Ethernet” section on page 117 for more details on this functionality.
On the PathBuilder S200 series switch links numbered 2 to 4 are not used and are
reserved for future configurations. WAN links are numbered 5 to 36 and provide up
to 32 WAN connection links which correspond to potential bridges.
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Bridge Hardware Components in PathBuilder S200 Series Switches
18 Bridging
Setting Up WAN Operation for Bridging
Setting Up W AN Operation for Bridging
Introduction With the 3Com Bridging Protocol option, you can use PathBuilder S200 series
switches to connect remot e LANs a cr oss a Wide Area Network (WAN), as shown in
Figure 13.
Codex Proprietary Protoc ol ID
LAN Connection Subaddress
Critical Parameter s
for WAN Operation
LAN
AAA
LAN
DDD
Node 1
Bridge 1
Half
Bridge 2
Half
Node 3
Bridge 2
Half
Bridge 3
Half
WAN
SVC Connectors
Node 2
Bridge 1
Bridge 3
Half
Half
LAN
CCC
Figure 13. Interface Connections Between WAN and LAN
Before you can use a PathBuilder S200 series switch as a bridge to connect LANs
over a WAN, you must configure the following two parameters in the Node record
for the bridge node. In most cases, use default values:
• Codex Proprietary Protocol ID
• LAN Connection Subaddress
You also need to configure the LAN Connection Table. Entries in this table are for
the WAN Adapter and specify co nnections going acr oss a wid e area ne twork, such as
X.25, Frame Relay, or other proprietary protocols.
Codex Proprietary
Protocol ID
The Protocol Identi fi er (ID) is placed o n t he Call User Data fie ld of t he Call Request
packet. This packet is generated by the Autocall used to establish a circuit for a
bridge link. If the bridge link is not configured to initiate an autocall, then this
configured value is ma tched with that found in an In coming Call pa cket to det ermine
if the call should be established.
To define the Codex Proprietary Protocol ID, select a value within the designated
range. Normally you would not configure a value different from the default value.
The only reason to use a different value is if the default value conflicts with one
already in use.
It is recommended that the Protocol ID value in all network nodes be the same.
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Setting Up WAN Operation for Bridging
LAN Connection
Subaddress
The LAN Connection Subaddresses identifies all LAN Connections. Incoming calls
with a network address consisting of the Node Address specified in the Node record
and the LAN Connection Subaddress, specified in the LAN Connection Table, are
verified and allowed to connect to the WAN Adapter in order to reach the LAN
bridges.
The LAN Connection Subaddress is appended to the calling address of the Call
Request packet if generated and sent by the WAN Adapter. Use the default value
unless it conflicts with an address already in use.
Refer to the “LAN Connection Table” section on page 31 for more details.
20 Bridging
Configuring the PathBuilder S200 Series Switch for Bridging Operation
Configuring the PathBuilder S200 Series Switch for Bridging
Operation
Introduction This section shows you how to configure a PathBuilder S200 series switch for
bridging operation.
What You Need to
Configure
When you are performing a Transparent Bridging operation, configure the following
records in the bridge node:
•Node Record
• LAN Port Record
•Bridge Record
• Bridge Link Record
• LAN Connection Table
• Optional Filter Tables
• LAN Server Subsystem (LSS) Record (optional)
• Autocall Mnemonic Table (Some of the WAN Adapter connections are
configured to Autocall.)
• Routing Table (At the destination node, a LAN Connection [LCON] entry is
needed for the WAN Adapter.)
For general details on configuring the Node record and the LAN Port record, refer to
the PathBuilder S200 Series Basics Protocols. For details on LAN Server Subsystem
configuration, see the “LAN Server Subsystem” section on page 120.
The following sections describe how to configure the records and tables critical for
performing bridging on a PathBuilder S200 series switch.
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Configuring the PathBuilder S200 Series Switch for Bridging Operation
Bridge Parameters
Bridge Port Record
Parameters
After you configure the Node record and the LAN Port record for the bridge node,
configure the Bridge parameters. Figure 14 shows the parameters that make up the
Bridge Parameters record.
Node: Address: Date: Time:
Menu: Configure Bridge Path:
Bridge Parameters
*Max Number of Bridge Links
*STPE Control
Bad Hello Threshold
Bad Hello Timeout
Learn Only Period
Aging Period
Bridge WAN Data Priority
Bridged Protocols
Local Bridge ID
Figure 14. Configure Bridge Parameters
Parameters These parameters make up the Bridge Parameter Record.
*Maximum Number of Bridge Links
Range: 36 to 250
Default: 36
Description: Specifies the maximum number of bridge links allowed.
Boot Type: A change to this parameter requires a Node boot to take effect.
22 Bridging
Configuring the PathBuilder S200 Series Switch for Bridging Operation
*STPE Control
Range: AUTO, MAN
Default: MAN
Description: The Spanning Tree Protocol Entity (STPE) module in the Path-
Builder S200 series switch provides automatic calculation of the
spanning tree. Spanning tr ee all ows f or the prop er support of single
route broadcast frames that occur in LANs. This parameter controls
how a bridge determines the Spanning Tree: either automatically
using the STPE, or manually using additional parameters in the
bridge link record.
• AUTO: The bridge participates in Spanning Tree Protocol
(STP) and automatically determines the single path between
LANs using the “Path Costs” assigned to the different links.
Bridge protocol data units (BPDUs) are special frames used to
continually communicate this information between bridges.
• MAN: The Spanning Tree is configured by the network
administrator. This is done using the STPE Link State
parameter found in the next section, “Bridge Link Parameters.”
Configure all bridges in your network to MANual if you are not an
expert user of Spanning Tree protocol operation. This prevents
problems in operation, especially when lower speed WAN links are
involved in forming bridges.
Note
If STPE Control parameter is set to MAN, the following parameter appears.
Bad Hello Threshold
Range: 10 to 30
Default: 15
Description: Use this parameter to generate alarms when some bridges are
configured AUTO and others are configured MAN in order to
detect nonmatching configurations.
A Bad Hello counter is incremented when a HELLO Protocol Data
Unit (PDU) is received while the STPE Control parameter is
configured to MAN. An event (alarm) is generated when the
counter exceeds the value of this parameter. The event is generated
only once during the Bad Hello Time.
Note
If STPE Control parameter is set to MAN, the following parameter appears.
Bad Hello Timeout
Range: 10 to 30
Default: 15
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Bad Hello Timeout
(continued)
Description: Represents the timeout value in minu tes. Th e Bad Hel lo coun te r is
reset when the timeout expires and can be used to control how
frequently the Hello counter reaches its alarm threshold.
Learn Only Period (used for Ethernet only)
Range: 2 to 604800
Default: 10
Description: The time in seconds that a bridge is prevented from forwarding
frames after the forwarding is cleared due to a node boot.
Aging Period (used for Ethernet only)
Range: 2 to 1000000
Default: 10
Description: Specify the time in seconds that a learned entry in the Forwarding
Table is allowed to remain in the table without being updated
(relearned). If t he e ntry is not updat ed within this time period, it is
discarded from the table.
Bridge WAN Data Pri o rity (used for Ethernet only)
Range: EXP, HIGH, MED, LOW
Default: HIGH
Description: Specify the transmission priority of the bridged data over the
WAN.
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Configuring the PathBuilder S200 Series Switch for Bridging Operation
Note
If STPE Control parameter value is AUTO, this parameter appears.
Bridged Protocols
Range: None, IP, IPX
Default: None
Description: Specify the routable protocols that can be bridged across BROUT
or BRID links. “None” specifies no routable protocols (IP, IPX)
will be bridged. “IP” specifies that IP packets can be bridged.
“IPX” specifies that IPX packets can be bridged.
Note
Any combination of the available selections may be specified by
summing, such as IP + IPX.
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Bridge Link Parameters
Introduction The bridge uses Bridge Li nks as connections to the LAN and WAN networks.
The LAN Bridge Link connects the bridge directly to the local LAN, and its
parameters control the characteristics of this connection.
The WAN Bridge Link parameters let you establish and maintain SVC connections
to a remote LAN bridge. The bridge views the LAN bridge links and the WAN
bridge links as links to the network s attached to it.
Bridge Link
Parameters
Figure 15 shows the Bridge Lin k parameters.
Node: Address: Date: Time:
Menu: Configure Bridge Path:
Bridge Parameters
Bridge Link Parameters
Entry Number
Bridge Type
Bridge ID
Hop Count Limit
Largest Frame Size
MAC Address Filter Action
Protocol Filter Action
NETBIOS Name Filter Action
STPE Link State
Link Mode
Virtual Ring Number
Figure 15. Configure Bridge Link Menu
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