3com 8807 Reference Guide

C

HAPTER

 27: BGP C

ONFIGURATION

 C

OMMANDS

If there are several routes available to one destination address, the route with 
smaller MED parameter can be selected as the final route item.

Do not use this command unless it is determined that the same IGP and routing 
selection mode are adopted by different autonomous systems.

confederation id as-number

BGP view

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.

Use the confederation id command to configure confederation identifier.

Use the undo confederation id command to cancel the BGP confederation 
specified by as-number argument.

By default, the confederation ID is not 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.

# 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 confederation while the peer 
200.1.1.1 is an external member of the AS confederation. For external members, 
Confederation 9 is a unified AS domain.

[SW8800] 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

 

[3Com-bgp] peer 10.1.1.1 group Confed38

 

[3Com-bgp] group Remote98 external