CCIE questions

jorgeeospina

So here is my first question. MPLS seems to be my nemesis. I am currently doing a lab that asks me to enable BGP in the core MPLS network only in the VPNv4 address family and disabled for the IPv4 address-family. My question is, why must BGP be enable in the VPNv4 address-family and not the IPv4 address-family. Is this absolutely necessary for BGP to work with MPLS or is it just LAB requirment for no reason? Also, how do the networks behave differently when BGP peers are enable only for the VPNv4 address family?

reaper81

By default the IPv4 address family is always activated. We can change this behavior in two ways. Either disable it globally under router bgp with no bgp default ipv4-unicast or under the address-family ipv4 and then the no neighbor x.x.x.x activate command. The reason is you will announce both VPNv4 routes and IPv4 routes otherwise in the core. This seems more of a lab scenario for in real life you would probably not even run BGP in the core, you would use MPLS only on the P routers. On the PE routers you will run BGP for both IPv4 and VPNv4 and IPv6 etc.

Also in real life it is very likely that you will be running route-reflectors since iBGP does not scale well otherwise due to requirement of full mesh.

thadizzy

reaper81 got it right, nothing to add there.
Just want to add that the CCIE lab have got absolutely nothing to do with reallife and the best practises, please understand that.