Cisco Systems 78-11741-02 manual Understanding Nlri Keywords and Address Families, IPC-350

Configuring Multiprotocol BGP Extensions for IP Multicast

Multiprotocol BGP Configuration Task List

Understanding NLRI Keywords and Address Families

Multiprotocol BGP was introduced in Cisco IOS Release 11.1(20)CC and Cisco IOS Release 12.0(2)S prior to it being integrated into Cisco IOS Release 12.1. In Cisco IOS Release 11.1(20)CC and later releases and Cisco IOS Release 12.0(2)S and later releases, the Cisco IOS software uses NLRI keywords to enable multiprotocol BGP over a BGP session and to populate unicast BGP prefixes in the unicast database and multicast BGP prefixes in the multicast database. In Cisco IOS Release 12.1, the Cisco IOS software uses separate address families to enable multiprotocol BGP over a BGP session and to populate unicast BGP prefixes in the unicast database and multicast BGP prefixes in the multicast database.

Cisco IOS Release 12.1 does not support the NLRI keywords. However, for backward compatibility, the NLRI keyword configuration of a Cisco router is automatically converted to an address family configuration when a router is upgraded to Cisco IOS Release 12.1. The following example shows an NLRI keyword configuration for a Cisco router that is running Cisco IOS Release 12.0(8)S:

router bgp 5

no synchronization

network 172.16.214.0 mask 255.255.255.0 nlri unicast multicast neighbor 172.16.214.34 remote-as 5

neighbor 172.16.214.38 remote-as 2 nlri unicast multicast neighbor 172.16.214.42 remote-as 5

neighbor 172.16.214.59 remote-as 5 no auto-summary

The following example shows the resulting address family configuration after the same router is upgraded to Cisco IOS Release 12.1:

router bgp 5

no synchronization

network 172.16.214.0 mask 255.255.255.0 neighbor 172.16.214.34 remote-as 5

neighbor 172.16.214.38 remote-as 2 neighbor 172.16.214.42 remote-as 5 neighbor 172.16.214.59 remote-as 5 no auto-summary

Note Although supported in Cisco IOS Release 12.1, the following sections do not explain how to configure the BGP-4 extensions for Virtual Private Network (VPN) address family prefixes. Configuring VPN address family prefixes will be explained in a later release of the Cisco IOS IP Configuration Guide and the Cisco IOS IP Command Reference, Volume 2 of 3: Routing Protocols.

Configuring a Multiprotocol BGP Peer

To configure multiprotocol BGP between two routers, use the following commands beginning in global configuration mode:

	Command	Purpose
Step 1
	Router(config)# router bgp autonomous-system	Configures a BGP routing process and places the
		router in router configuration mode.
Step 2
	Router(config-router)# neighbor ip-addressremote-as	Adds the IP address of the neighbor in the remote
	autonomous-system-number	autonomous system to the multiprotocol BGP
		neighbor table of the local router.

Cisco IOS IP Configuration Guide

IPC-350