Configuring a BGP Confederation
Context
A confederation divides an AS into sub-ASs. Within each sub-AS, IBGP peers establish full-mesh connections or have an RR configured. Sub-ASs establish EBGP connections. On a large BGP network, configuring a confederation can reduce the number of IBGP connections, simplify routing policy management, and improve route advertisement efficiency.
Other devices may implement the confederation not in accordance with RFC 3065. You can configure confederation compatibility to make standard devices compatible with nonstandard devices.
BGP peers within a BGP confederation do not change the next hop of BGP routes to their local IP addresses before advertising the routes to each other, unless the peer next-hop-local command is run.
Procedure
- Run system-view
The system view is displayed.
- Run bgp { as-number-plain | as-number-dot }
BGP is enabled and the BGP view is displayed.
- Run confederation id { as-number-plain | as-number-dot }
A confederation ID is configured.
By default, no BGP confederation is configured.
An old speaker that has a 2-byte AS number cannot be in the same confederation with a new speaker that has a 4-byte AS number. Otherwise, a routing loop may occur. This is because the AS4_Path attribute does not support confederations.
- Run confederation peer-as { as-number-plain | as-number-dot } &<1-32>
A sub-AS number is configured for a confederation.
By default, no sub-AS number of the confederation is configured.
- (Optional) Run confederation nonstandard
Confederation compatibility is configured.
By default, confederations comply with RFC 3065.
- Run commit
The configuration is committed.
