BGP soft session reset

Unanswered Question
Nov 5th, 2008

hi,

what's the difference between the two methods of softly resetting BGP sessions? I mean between :

"clear ip bgp xxxx soft in"

and

Route Refresh

?

How do I configure Route Refresh by the way?

I have this problem too.
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milan.kulik Wed, 11/05/2008 - 13:12

Hi,

here is the explanation from "clear bgp soft" Command reference:

"Use the clear bgp soft command to trigger a soft reset of the specified address families for the specified group of neighbors. This command is useful if you change the inbound or outbound policy for the neighbors, or any other configuration that affects the sending or receiving of routing updates.

If an outbound soft reset is triggered, BGP resends all routes for the address family to the given neighbors.

If an inbound soft reset is triggered, BGP by default sends a REFRESH request to the neighbor, if the neighbor has advertised the ROUTE_REFRESH capability. To determine whether the neighbor has advertised the ROUTE_REFRESH capability, use the show bgp neighbors command, and look for the following line of output:

Received route refresh capability from peer.

If the neighbor does not support route refresh, but the soft-reconfiguration inbound command is configured for the neighbor, then BGP uses the routes cached as a result of the soft-reconfiguration inbound command to perform the soft reset.

If you want BGP to use the cached routes even if the neighbor supports route refresh, you can use the always keyword when configuring the soft-reconfiguration inbound command.

If the neighbor does not support route refresh and the soft-reconfiguration inbound command is not configured, then inbound soft reset is not possible. In this case, an error is printed."

So you can't configure Route Refresh capability, it's either supported by the IOS or not.

BR,

Milan

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