BGP prefix list in - clear ip bgp

I am looking at blocking routes coming into BGP.

I have a simple topology and this configuration- I am just blocking the prefix 2.2.2.2/32 into R1

R1 router bgp 65500
 no synchronization
 bgp log-neighbor-changes
 network 1.1.1.1 mask 255.255.255.255
 network 10.0.12.0 mask 255.255.255.0
 network 10.0.13.0 mask 255.255.255.0
 neighbor 10.0.12.2 remote-as 65501
 neighbor 10.0.12.2 prefix-list block2 in

ip prefix-list block2 seq 5 deny 2.2.2.2/32

 

My question is what timer determines when this changes? When does an automatic route-refresh occur?

Because as far as I can tell it will stay there forever until you do a manual route-refresh?

I normally just do a quick clear ip bgp * soft in after anything like this but - wondered today how long it would take if I didn't?

Just trying to understand BGP more

 

Thanks

 

Roger

 

 

 

 

Comments

  •  

    I normally just do a quick clear ip bgp * soft in after anything like this but - wondered today how long it would take if I didn't?

    Hi Roger,

    BGP needs to be clear either soft or hard in order for your filtering to work in this case. Simply, issue "clear ip bgp * soft" command to avoid peer reset.

    HTH

  • My question is what timer determines when this changes? When does an automatic route-refresh occur?

     

    There is no automatic/periodic/panic route refresh in BGP. BGP is designed to favor stability over fast convergence.

  • Thanks for confirming this, it is what I understood to be the case but could not find anything written about it.

     

    Thanks

     

    Roger

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