3Com 3C13636 Configuration Manual page 684

3Com Router 3000 Ethernet Family
Configuration Guide
6.2.14 Configuring BGP AS Confederation Attribute
Confederation provides another solution to handle the booming IBGP network
connections inside an AS. It divides an AS into multiple sub-ASs, with the IBGP peers
inside each sub-AS fully connected and connecting to other sub-ASs in the
confederation.
The shortcomings of confederation lie in: it is required that the router be reconfigured
upon switching from non-confederation to confederation solution, and that the logic
topology be basically changed. Furthermore, the path selected via confederation may
not be the best path if there is no manually-set BGP policy.
I. Configuring confederation ID
In the sight of the BGP speakers that are not included in the confederation, multiple
sub-ASs that belong to the same confederation are a whole. The external network does
not need to know the status of internal sub-ASs, and the confederation ID is the AS
number identifying the confederation as a whole.
Perform the following configuration in BGP view.
Table 6-33 Configure confederation ID
Configure confederation ID
Cancel confederation ID
By default, the confederation ID is not configured.
The configured confederation ID cannot be the same as the existing AS number of a
peer or a peer group.
II. Configuring the sub-ASs belonging to a confederation
Configure confederation ID first, and then configure the sub-AS belonging to the
confederation. One confederation includes up to 32 sub-ASs. The as-number used
upon configuring sub-AS belonging to the confederation is valid within the
confederation.
Perform the following configuration in BGP view.
Table 6-34 Configure the sub-ASs belonging to a confederation
Configure the sub-ASs belonging to a
confederation
Cancel the specified sub-AS in the
confederation
Operation
Operation
3Com Corporation
6-19
Chapter 6 BGP Configuration
Command
confederation id as-number
undo confederation id
Command
confederation peer-as as-number-1
[ ... as-number-n ]
undo confederation
[ as-number-1 ] [ ...as-number-n ]
peer-as