3Com S7902E, Configuration Manual

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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:
To do… Use the command… Remarks
Enter system view 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.
Remove private AS numbers from updates to a peer/peer group
Follow these steps to remove private AS numbers from updates to a peer/peer group:
To do… Use the command… Remarks
Enter system view 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.
Tuning and Optimizing BGP Networks
Prerequisites
BGP connections have been created.
Configuring BGP Keepalive Interval and Holdtime
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: