3com S7906E Manuel De Montage

 

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As shown in the above figure, CE 1 and CE 2 use the same AS number of 800. If AS number 

substitution for CE 2 is configured on PE 2, when PE 2 receives a BGP update sent from CE 1, it 

replaces AS number 800 as its own AS number 100. Similar configuration should also be made on PE 

1.  

Follow these steps to configure AS number substitution for a peer/peer group: 

Enter system view 

— 

Enter BGP view 

bgp as-number 

— 

Replace the AS number of a peer/peer 
group in the AS_PATH attribute as the 
local AS number 

peer { group-name | 
ip-address } substitute-as 

Optional 

Not configured by default.

 

Improper AS number substitution configuration may cause route loops; use this command with caution. 

 

Follow these steps to remove private AS numbers from updates to a peer/peer group: 

Enter system view 

— 

Enter BGP view 

bgp as-number 

— 

Configure BGP to remove private AS 
numbers from the AS_PATH attribute of 
updates to a peer/peer group 

peer { group-name | 
ip-address } public-as-only 

Optional 

By default, BGP updates 
carry private AS 
numbers. 

 

BGP connections have been created. 

After establishing a BGP connection, two routers send keepalive messages periodically to each other to 

keep the connection. If a router receives no keepalive or update message from the peer within the 

holdtime, it tears down the connection. 

If two parties have the same timer assigned with different values, the smaller one is used by the two 

parties. 

Follow these steps to configure BGP keepalive interval and holdtime: