Configuring a BGP Confederation

On a large BGP network, configuring a BGP confederation reduces the number of IBGP connections and simplifies routing policy management, which increases the route advertisement efficiency.

Usage Scenario

A confederation is a solution to the increasing number of IBGP connections in an AS. The confederation divides an AS into multiple sub-ASs. In each sub-AS, IBGP peer relationships are set up or an RR is configured on one of the IBGP peers. EBGP connections are set up between sub-ASs.

Compared with RRs, confederations facilitate IGP extensions.

Pre-configuration Tasks

Before configuring a BGP confederation, complete the following tasks:

Configure link layer protocol parameters and assigning IP addresses to the interfaces to ensure that the status of the link layer protocol of the interface is Up.
Configure basic BGP functions.

Procedure

Configure a BGP Confederation.
Perform the following steps on the BGP device:
1. Run system-view
  The system view is displayed.
2. Run bgp as-number
  The BGP view is displayed.
3. Run confederation id as-number
  The confederation ID is set.
4. Run confederation peer-as as-number &<1-32>
  The number of the sub-AS of other EBGP peers is set.
  
  The parameter as-number used is valid only in the confederation.
  
  The confederation id and confederation peer-as commands must be run for all the EBGP peers in a confederation, and the EBGP peers must have the same confederation ID.
  
  The old speaker supporting 2-byte AS numbers and the new speaker supporting 4-byte AS numbers cannot exist in the same confederation. Otherwise, routing loops may occur because AS4_Path does not support confederations.
5. Run commit
  The configuration is committed.
Configure the compatibility of the confederation.
If some routers in a confederation do not comply with the standard protocols, you can perform the following steps so that the local device is compatible with them:
1. Run system-view
  The system view is displayed.
2. Run bgp as-number
  The BGP view is displayed.
3. Run confederation nonstandard
  The compatibility of the confederation is configured.
4. Run commit
  The configuration is committed.

Checking the Configurations

Run the following command to check the previous configuration:

Run the display bgp peer [ ipv4-address ] verbose command to check detailed information about the peer.
Run the display bgp routing-table [ network ] [ mask | mask-length ] [ longer-prefixes ] command to check information about the BGP routing table.