neighbor activate bgp

[Kashish_Patel]

I recently saw the command "neighbor x.x.x.x activate" under router bgp configuration. Neighbors are automatically activated if configured properly. Then why do we need this command?

[cadet alain]

Hi,

This command is used under family-address to tell other peers  which family-address we support( ipv4/ipv6 unicast, ipv4/ipv6 multicast, ipv4/ipv6 VPN).This is for MP-BGP but now you can use it with BGP as replacement for default ipv4 configuration.

Regards

Alain

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[Kashish_Patel]

Thanks Cadet.

But why will anybody want to use this command when normal BGP config works just fine? I guess there is no need, just that if IPv6 (or protocol other than IPv4) is used, then this command is a must as IPv4 is default for BGP...Is that right?

[Ravindra Simpi]

This can be used on CE VRFs. CE IP addresses are known only at appropriate VRF level hence it makes no sense in defining the neighbor at process level.

As the IPv4 address families are used to represent routing session for protocols that use IPv4 address prefix. We need to activate in IPv4 routing session.

[paul driver]

Hello

I guess there is no need, just that if IPv6 (or protocol other than  IPv4) is used, then this command is a must as IPv4 is default for  BGP...Is that right? -  NO that inst correct

By default bgp assumes you want to use ipv4 unicast bgp, however if you disable this prior to defining you bgp peers

no bgp default ipv4-unicast than you need to specify this  activate command  so that peer will establish.

router bgp xxx

no bgp default ipv4-unicast

bgp log-neighbor-changes

neighbor x.x.x.x remote-as xx

address-family ipv4

neighbor x.x.x.x activate

res

Paul

Hope this have been helpful.

Thanks.