Software Version: 7750 SR OS 5.0
February 2007
Document Part Number: 93-0073-03-01
*93-0073-03-01*
This document is protected by copyright. Except as specifically permitted herein, no portion of the provided information can be
reproduced in any form, or by any means, without prior written permission from Alcatel-Lucent.
This guide describes logical IP routing interfaces, virtual routers, IP and MAC-based filtering, and
cflowd support provided by the 7750 SR OS and presents configuration and implementation
examples.
This document is organized into functional chapters and provides concepts and descriptions of the
implementation flow, as well as Command Line Interface (CLI) syntax and command usage.
Audience
Preface
This manual is intended for network administrators who are responsible for conf iguring the 7750
SR-Series routers. It is assumed that the network administrators have an understanding of
networking principles and configurations. Protocols, standards, and services described in this
manual include the following:
•IP router configuration
•V irtual routers
•IP and MAC-based filters
•Cflowd
7750 SR OS Router Configuration GuidePage 13
Preface
List of Technical Publications
The 7750 SR documentation set is composed of the following books:
•7750 SR OS Basic System Configuration Guide
This guide describes basic system configurations and operations.
•7750 SR OS System Management Guide
This guide describes system security and access configurations as well as event logging
and accounting logs.
•7750 SR OS Interface Configuration Guide
This guide describes card, Media Dependent Adapter (MDA), and port provisioning.
•7750 SR OS Router Configuration Guide
This guide describes logical IP routing interfaces and associated attributes such as an IP
address, port, link aggregation group (LAG) as well as IP and MAC-based filtering,
VRRP, and Cflowd.
•7750 SR OS Routing Protocols Guide
This guide provides an overview of routing concepts and provides configuration examples
for RIP, OSPF, IS-IS, Multicast, BGP, and route policies.
•7750 SR OS MPLS Guide
This guide describes how to configure Multiprotocol Label Switching (MPLS) and Label
Distribution Protocol (LDP).
•7750 SR OS Services Guide
This guide describes how to configure service parameters such as service distribution
points (SDPs), customer information, user services, service mirroring and Operations,
Administration and Management (OAM) tools.
•7750 SR OS Triple Play Guide
This guide describes Triple Play services and support provided by the 7750 SR and
presents examples to configure and implement various protocols and services.
•7750 SR Quality of Service Guide
This guide describes how to configure Quality of Service (QoS) policy management.
Page 147750 SR OS Rout er Configuration Guide
Technical Support
If you purchased a service agreement for your 7750 SR-Series router and related products from a
distributor or authorized reseller, contact the technical support staff for that distributor or reseller
for assistance. If you purchased an Alcatel-Lucent service agreement, contact your welcome center
at:
This chapter provides process flow information to configure routing entities, virtual routers, IP and
MAC filters, and Cflowd.
Alcatel-Lucent 7750 SR-Series Router Configuration
Process
Table 1 lists the tasks necessary to configure logical IP routing interfaces, virtual routers, IP and
MAC-based filtering, and Cflowd.
This guide is presented in an overall logical configuration flow. Each section describes a software
area and provides CLI syntax and command usage to configure parameters for a functional area.
Table 1: Configuration Process
AreaTaskChapter
Router
configuration
Protocol
configuration
ReferenceList of IEEE, IETF, and other proprietary entities.Standards and Protocol Supp ort on
Configure router parameters, including router
interface and addresses, router ID, autonomous
systems, and confederations.
VRRPVRRP on page 169
IP and MAC filtersFilter Policies on page 275
CflowdCflowd on page 429
IP Router Configuration on page
19
page 715
7750 SR OS Router Configuration GuidePage 17
Getting Started
Page 187750 SR OS Router Configuration Guide
In This Chapter
This chapter provides information about commands required to configure basic router parameters.
Topics in this chapter include:
•Configuring IP Router Parameters on page 20
→ Interfaces on page 20
IP Router Configuration
→ Router ID on page 22
→ Autonomous Systems (AS) on page 23
→ Confederations on page 24
→ Proxy ARP on page 26
→ Internet Protocol Versions on page 27
•Router Configuration Process Overview on page 36
•Configuration Notes on page 39
7750 SR OS Router Configuration GuidePage 19
Configuring IP Router Parameters
Configuring IP Router Parameters
In order to provision services on a 7750 SR-Series router, logical IP routing interfaces must be
configured to associate attributes such as an IP address, port or the system with the IP interface.
A special type of IP interface is the system interface. A system interface must have an IP address
with a 32-bit subnet mask. The system interface is used as the router identifier by higher-level
protocols such as OSPF and BGP, unless overwritten by an explicit router ID.
The following router features can be configured:
•Interfaces
•IP Addresses
•Router ID
•Autonomous Systems (AS)
•Confederations
•DHCP Relay
•Internet Protocol Versions
Interfaces
7750 SR-Series routers use different types of interfaces for various functions. Interfaces must be
configured with parameters such as the interface type (network and system) and address. A port is
not associated with a system interface. An interface can be associated with the system (loopback
address).
Network Interface
A network interface (a logical IP routing interface) can be configured on one of the following
entities:
•A physical or logical port
•A SONET/SDH channel
Page 207750 SR OS Router Configuration Guide
System Interface
The system interface is associated with the network entity (such as a specific router or switch), not
a specific interface. The system interface is also referred to as the loopback address. The system
interface is associated during the configuration of the following entities:
•The termination point of service tunnels
•The hops when configuring MPLS paths and LSPs
•The addresses on a target router for BGP and LDP peering
The system interface is used to preserve connectivity (when routing reconvergence is possible)
when an interface fails or is removed. The system interface is used as the router identifier. A
system interface must have an IP address with a 32-bit subnet mask.
IP Router Configuration
7750 SR OS Router Configuration GuidePage 21
Configuring IP Router Parameters
IP Addresses
Creating an IP Address Range
An IP address range can be reserved for exclusive use for services by defining the
config>router>service-prefix command. When the service is configured, the IP address
must be in the range specified as a service prefix. If no service prefix command is configured, then
no limitation exists.
Addresses in the range of a service prefix can be allocated to a network port unless the exclusive
parameter is used. Then, the address range is exclusively reserved for services.
When defining a range that is a superset of a previously defined service prefix, the subset will be
replaced with the superset definition. For example, if a service prefix exists for 10.10.10.0/24, and
a new service prefix is configured as 10.10.0.0/16, then the old address (10.10.10.0/24) will be
replaced with the new address (10.10.0.0/16).
Router ID
When defining a range that is a subset of a previously defined service prefix, the subset will
replace the existing superset, providing addresses used by services are not affected; for example, if
a service prefix exists for 10.10.0.0/16, and a new service prefix is configured as 10.10.10.0/24,
then the 10.10.0.0/16 entry will be removed, provided that no services are configured that use
10.10.x.x addresses other than 10.10.10.x.
The router ID, a 32-bit number, uniquely identifies the router within an autonomous system (AS)
(see Autonomous Systems (AS) on page 23). In protocols such as OSPF, routing information is
exchanged between areas, groups of networks that share routing information. It can be set to be the
same as the loopback address. The router ID is used by both OSPF and BGP routing protocols in
the routing table manager instance.
There are several ways to obtain the router ID. On each 7750 SR-Series router, the router ID can be
derived in the following ways.
•Define the value in the
router ID.
•Configure the system interface with an IP address in the
ip-int-name
config>router router-id context, then the system interface acts as the router ID.
•If neither the system interface or router ID are implicitly specified, then the router ID is
inherited from the last four bytes of the MAC address.
•The router can be derived on the protocol level; for example, BGP.
context. If the router ID is not manually configured in the
config>router router-id context. The value becomes the
config>router>interface
Page 227750 SR OS Router Configuration Guide
Autonomous Systems (AS)
Networks can be grouped into areas. An area is a collection of network segments within an AS that
have been administratively assigned to the same group. An area’s topology is concealed from the
rest of the AS, which results in a significant reduction in routing traffic.
Routing in the AS takes place on two levels, depending on whether the source and destination of a
packet reside in the same area (intra-area routing) or different areas (inter-area routing). In intraarea routing, the packet is routed solely on information obtained within the area; no routing
information obtained from outside the area can be used. This protects intra-area routing from the
injection of bad routing information.
Routers that belong to more than one area are called area border routers. All routers in an AS do
not have an identical topological database. An area border router has a separate topological
database for each area it is connected to. Two routers, which are not area border routers, belonging
to the same area, have identical area topological databases.
Autonomous systems share routing information, such as routes to each destination and information
about the route or AS path, with other ASs using BGP. Routing tables contain lists of next hops,
reachable addresses, and associated path cost metrics to each router. BGP uses the information and
path attributes to compile a network topology.
IP Router Configuration
7750 SR OS Router Configuration GuidePage 23
Configuring IP Router Parameters
Confederations
Configuring confederations is optional and should only be implemented to reduce the IBGP mesh
inside an AS. An AS can be logically divided into smaller groupings called sub-confederations and
then assigned a confederation ID (similar to an autonomous system number). Each subconfederation has fully meshed IBGP and connections to other ASs outside of the confederation.
The sub-confederations have EBGP-type peers to other sub-confederations within the
confederation. They exchange routing information as if they were using IBGP. Parameter values
such as next hop, metric, and local preference settings are preserved. The confederation appears
and behaves like a single AS.
Confederations have the following characteristics.
•A large AS can be sub-divided into sub-confederations.
•Routing within each sub-confederation is accomplished via IBGP.
•EBGP is used to communicate between sub-confederations.
•BGP speakers within a sub-confederation must be fully meshed.
•Each sub-confederation (member) of the confederation has a different AS number. The AS
numbers used are typically in the private AS range of 64512 — 65535.
To migrate from a non-confederation configuration to a confederation configuration requires a
major topology change and configuration modifications on each participating router. Setting BGP
policies to select an optimal path through a confederation requires other BGP modifications.
Page 247750 SR OS Router Configuration Guide
IP Router Configuration
There are no default confederations. Router confederations must be explicitly created. Figure 1
depicts a confederation configuration example.
Confederation 2002
AS 100
ALA-A
Confederation Member 1
AS 200
ALA-BALA-C
ALA-D
AS 400
Confederation Member 2
Confederation Member 3
AS 500
ALA-H
AS 300
ALA-EALA-F
Figure 1: Confederation Configuration
ALA-G
SRSG005
7750 SR OS Router Configuration GuidePage 25
Configuring IP Router Parameters
Proxy ARP
Proxy ARP is the technique in which a router answers ARP requests intended for another node.
The router appears to be present on the same network as the “real” node that is the target of the
ARP and takes responsibility for routing packets to the “real” destination. Proxy ARP can help
nodes on a subnet reach remote subnets without configuring routing or a default gateway.
Typical routers only support proxy ARP for directly attached networks; the 7750 SR-Series is
targeted to support proxy ARP for all known networks in the routing instance where the virtual
interface proxy ARP is configured.
In order to support DSLAM and other edge like environments, 7750 SR-Series proxy ARP
supports policies that allow the provider to configure prefix lists that determine for which target
networks proxy ARP will be attempted and prefix lists that determine for which so urce hosts proxy
ARP will be attempted.
In addition, the 7750 SR OS proxy ARP implementation will support the ability to respond for
other hosts within the local subnet domain. This is needed in environments such as DSL where
multiple hosts are in the same subnet but can not reach each other directly.
Static ARP is used when a 7750 SR OS needs to know about a device on an interface that cannot or
does not respond to ARP requests. Thus, the 7750 SR OS configuration can state that if it has a
packet that has a certain IP address to send it to the corresponding ARP address. Use proxy ARP so
the 7750 SR responds to ARP requests on behalf of another device.
Page 267750 SR OS Router Configuration Guide
Internet Protocol Versions
The 7750 SR OS implements IP routing functionality, providing support for IP version 4 (IPv4)
and IP version 6 (IPv6). IP version 6 (IPv6) (RFC 1883, Internet Protocol, Version 6 (IPv6)) is a
newer version of the Internet Protocol designed as a successor to IP version 4 (IPv4) (RFC-791,
Internet Protocol). The changes from IPv4 to IPv6 effect the following categories:
•Expanded addressing capabilities — IPv6 increases the IP address size from 32 bits (IPv4)
to 128 bits, to support more levels of addressing hierarchy, a much greater number of
addressable nodes, and simpler auto-configuration of addresses. The scalability of
multicast routing is improved by adding a scope field to multicast addresses. Also, a new
type of address called an anycast address is defined that is used to send a packet to any one
of a group of nodes.
•Header format simplification — Some IPv4 header fields have been dropped or made
optional to reduce the common-case processing cost of packet handling and to limit the
bandwidth cost of the IPv6 header.
•Improved support for extensions and options — Changes in the way IP header options are
encoded allows for more efficient forwarding, less stringent limits on the length of
options, and greater flexibility for introducing new options in the future.
IP Router Configuration
•Flow labeling capability — The capability to enable the labeling of packets belonging to
particular traffic flows for which the sender requests special handling, such as non-default
quality of service or “real-time” service was added in IPv6.
•Authentication and privacy capabilities — Extensions to support authentication, data
integrity, and (optional) data confidentiality are specified for IPv6.
Version4-bit Internet Protocol version number = 6.
Prio. 4-bit priority value.
Flow Label24-bit flow label.
Payload Length 16-bit unsigned integer. The length of payload, for example, the rest of the packet
following the IPv6 header, in octets. If the value is zero, the payload length is
carried in a jumbo payload hop-by-hop option.
Next Header 8-bit selector. Identifies the type of header immediately following the IPv6 header.
This field uses the same values as the IPv4 protocol field.
Hop Limit 8-bit unsigned integer. Decremented by 1 by each node that forwards the packet.
The packet is discarded if the hop limit is decremented to zero.
Source Address 128-bit address of the originator of the packet.
Destination Address 128-bit address of the intended recipient of the packet (possibly not the ultimate
recipient if a routing header is present).
Page 287750 SR OS Router Configuration Guide
IPv6 Applications
Examples of the IPv6 applications supported by the 7750 SR OS include:
•IPv6 Internet exchange peering — Figure 3 shows an IPv6 Internet exchange where
multiple ISPs peer over native IPv6.
IP Router Configuration
IPv6 IX
ISP A
Peering
ISP B
Figure 3: IPv6 Internet Exchange
•IPv6 transit services — Figure 4 shows IPv6 transit provided by an ISP.
Customer 1
2001:0410:0001:/48
ISP
2001:0410::/32
Customer 2
2001:0410:0002:/4
IPIPE_007
IPIPE_008
Figure 4: IPv6 Transit Services
7750 SR OS Router Configuration GuidePage 29
Configuring IP Router Parameters
•IPv6 services to enterprise customers and home users — Figure 5 shows IPv6 connectivity
to enterprise and home broadband users.
Enterprise
DSL, Cable
FTTH
IPv6 Core
IPv6 Broadband Users
ISP
IPIPE_009
Figure 5: IPv6 Services to Enterprise Customers and Home Users
•IPv6 over IPv4 relay services — IPv6 over IPv4 tunnels are one of many IPv6 transition
methods to support IPv6 in an environment where not only IPv4 exists but native IPv6
networks depend on IPv4 for greater IPv6 connectivity. 7750 SR OS supports dynamic
IPv6 over IPv4 tunneling. The ipv4 source and destination address are taken from
configuration, the source address is the ipv4 system address and the ipv4 destination is the
next hop from the configured 6over4 tunnel.
IPv6 over IPv4 is an automatic tunnel method that gives a prefix to the attached IPv6
network. Figure 6 shows IPv6 over IPv4 tunneling to transition from IPv4 to IPv6.
6to4
6to4
IPv4 Clo u d
Figure 6: IPv6 over IPv4 Relay Services
Page 307750 SR OS Router Configuration Guide
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