3Com Switch 7750 Series
Command Reference Guide – Routing Protocol Chapter 5 BGP Configuration Commands
5-5
5.1.5 confederation id Syntax
confederation id as-number
undo confederation id
View
BGP view
Parameter
as-number: The ID of BGP AS confederation. It is equal to the AS number which
contains the AS numbers of multiple sub-ASs. The range is 1 to 65535.
Description
Use the confederation id command to configure confederation identifier.
Use the undo confederation id command to cancel the BGP confederation specified
by the as-number argument.
By default, no confederation ID is configured.
Confederation can be adopted to solve the problem of too many IBGP full connections
in a large AS domain. The solution is, first dividing the AS domain into several smaller
sub-ASs, and each sub-ASs remains full-connected. These sub-ASs form a
confederation. Key BGP attributes of the route, such as next hop, MED, local
preference, are not discarded across each sub-ASs. The sub-ASs still look like a
whole from the point of view of a confederation although these sub-ASs have EBGP
relations. This can assure the integrality of the former AS domain, and ease the
problem of too many connections in the domain
Related command: confederation nonstandard, confederation peer-as.
Example
# Confederation 9 consists of four sub-ASs, namely, 38, 39, 40, and 41. Here, the
peer 10.1.1.1 is an internal member of the AS confede rat ion wh ile t he pee r 200.1.1.1
is an external member of the AS confederation. For external members, Confederation
9 is a unified AS domain. The following gives an example of the configuration of AS
41.
<3Com> system-view
System View: return to User View with Ctrl+Z.
[3Com] bgp 41
[3Com-bgp] confederation id 9
[3Com-bgp] confederation peer-as 38 39 40
[3Com-bgp] group Confed38 external
[3Com-bgp] peer Confed38 as-number 38