I wish to remove one of my subnets from being advertised from my AS on my mesh of iBGP peers. After performing a "no network x.x.x.x" statement, must I then issue a "clear ip bgp * " command ? I understand that this command will reset the BGP sessions with each peer, causing all external routes from other ASs to be removed from our routing tables for up to a few minutes - thus causing loss of connectivity between our AS and the rest of the ASs. Since it is our intention to only prevent a route from being advertised outbound to our eBGP peers, I feel that the "clear ip bgp *" command could be unnecessarily disruptive.
00:07:00: BGP: 10.10.10.11 update run completed, ran for 8ms, neighbor version 4, start version 5, throttled to 5, check point net 0.0.0.0
You may notice the version listed above (first one is 4 when the update is sent to remove the route, second is 5 when the route is added and the update sent), it will relate to the tblver (table version) in the 'sh ip bg sum' command.
I hope you don't think I am trying to disagree with you. Cisco Press book on CCNP routing that I am studying states that it is necessary to reset TCP sessions between nieghbors after configuration changes in BGP4 with following command:
clear ip bgp * | address soft in | out
Says that the soft option will not tear down the sessions but it resends the updates. The in and out options allow the configuration of inbound and outbound soft updates and that the default is for both.
From what I see in your post, this command is not necessary in this case. Could you let us know in what situations, when configuration changes are being made, that this command would be needed? Thanks
When a network is added or removed, BGP will automatically send an Update message informing it's peers about the change. Just like any other routing protocol. If BGP required a manual intervention, there would be way too much outdated info/black holes in routing tables.
The command 'clear ip bgp' is needed only when you have changed the BGP policy (eg route-map/MED/Local/pref/weight/community/etc.) It is a total reset, which resets the peer state to IDLE and then restarts the peering process.
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...
Attached policy provides CLI access to the Cisco 4G router over text messaging. Two files are in the attached .tar file:
2. PDF with instructions on how to load and use the .tcl file.