bgp, vpnv4, configuration

[Q987654456]

To exchange VPNv4 prefixes, before configure bgp-session for the neighbor vpnv4, I must configure bgp-session in Global (under "router bgp yyyyy"),

otherwise router say:
(config)#router bgp yyyyy
(config-router)#address-family vpnv4
(config-router-af)#neighbor x.x.x.x remote-as yyyyy
% General session commands not allowed under the address family

I don't want exchange IPv4 prefixes. Why I must configure BGP neighbour in Global? Can anybody explain it?

Best regards,

Artemiy

[Nagendra Kumar Nainar · Accepted solution]

Hi Artemiy,

This is just an optimized way of configuring the neighbors.  In IOS or IOS-XE, you can configure "neighbor <> remote-as <>" under router bgp prompt and just activate it under the relevant address-families. For example, 2 BGP speakers may need to exchange prefixes belonging to different address familes like IPv4, IPv6, MVPNv4, EVPN, MVPNv6, VPNv4, VPNv6 etc. Instead of confguring "neighbor <> remote-as <>" under each address family separately, this is an optimzed way of configuring it once under router bgp prompt and enable it under respective address family.

HTH,

Nagendra