Setup Guide

Conguring BGP Confederations
Another way to organize routers within an AS and reduce the mesh for IBGP peers is to congure BGP confederations.
As with route reectors, BGP confederations are recommended only for IBGP peering involving many IBGP peering sessions per router.
Basically, when you congure BGP confederations, you break the AS into smaller sub-AS, and to those outside your network, the
confederations appear as one AS. Within the confederation sub-AS, the IBGP neighbors are fully meshed and the MED, NEXT_HOP, and
LOCAL_PREF attributes are maintained between confederations.
To congure BGP confederations, use the following commands.
• Species the confederation ID.
CONFIG-ROUTER-BGP mode
bgp confederation identifier as-number
– as-number: from 0 to 65535 (2 Byte) or from 1 to 4294967295 (4 Byte).
• Species which confederation sub-AS are peers.
CONFIG-ROUTER-BGP mode
bgp confederation peers as-number [... as-number]
– as-number: from 0 to 65535 (2 Byte) or from 1 to 4294967295 (4 Byte).
All Confederation routers must be either 4 Byte or 2 Byte. You cannot have a mix of router ASN support.
To view the conguration, use the show config command in CONFIGURATION ROUTER BGP mode.
Conguring a BGP VRF address family
To perform BGP conguration between two neighbors that must exchange IPv6 or IPv4 VRF information, use the following commands.
Following are the steps to congure BGP VRF address-family between two peers.
• Congure a VRF routing table.
CONFIG mode
ip vrf vrf-name
For more information on VRF conguration, see Virtual Routing and Forwarding (VRF).
• Enter the router conguration mode and the AS number.
CONFIG mode
router bgp as-number
• Specify the IPv4 address family conguration.
CONFIG-ROUTER-BGP mode
address-family {ipv4 [multicast] | ipv6 unicast} vrf vrf-name
vrf vrf-name — Species the name of VRF instance associated with the IPv4 or IPv6 address-family conguration.
• Add the IP address of the neighbor in the specied AS to the IPv4 MBGP neighbor table.
CONFIG-ROUTER-BGP-AF mode
neighbor {ip-address | ipv6–address | peer-group-name} remote-as as-number
• Enable the neighbor.
CONFIG-ROUTER-BGP mode
Border Gateway Protocol (BGP)
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