bgp soft reconfiguration

[carl_townshend]

Hi all

I have seen the command bgp soft reconfiguration inbound and outbound,

can anyone explain what this command does? I have read up but cant understand how it works, also what does the inbound and outbound do ?

cheers

Carl

[Peter Paluch]

Hello Carl,

Aaah, my favourite topic

Would you mind checking the following threads? I tried to explain this topic several times and it pops up repeatedly. Of course, I am willing to re-explaing it again should these threads be insufficient - just let me know.

https://supportforums.cisco.com/message/829228#829228

https://supportforums.cisco.com/message/3523990#3523990

Best regards,

Peter

[adnane dakna]

Hi ,

us I understand , when we add command "neighbor x.y.z.t soft-reconfiguration inbound " the router create database containing all advertised routes to neigbhor x.y.z.t , this command is useful when debugging BGP routes issues.

[Peter Paluch]

Hi Adnane,

when we add command "neighbor x.y.z.t soft-reconfiguration inbound " the  router create database containing all advertised routes to neigbhor  x.y.z.t

Not advertised to but rather received from neighbor x.y.z.t.

this command is useful when debugging BGP routes issues.

The primary purpose of soft-configuration inbound was to allow changing the input policy without the need to tear down and reestablish the BGP peering with the neighbor. It was accomplished, principially, by storing all received prefixes unfiltered and unchanged, and subsequently filtering this "pristine" database with the input policies into another database. The fact that the router stores all received prefixes unfiltered may help in certain debugging situations, but in general, the soft-reconfig inbound is not primarily a debugging tool.

Best regards,

Peter

[adnane dakna]

Thanks peter , i will correct my knowldge.