ipv4 and vpnv4

[kousik.dutta@ge.com]

Hi,

The scenario is my WAN router is connected with MPLS peering PE router with same AS number and LAN also configured in down steam. So in that case IBGP has been configured with same AS number with IPV4 and VPNv4.

So anyone can describe whats the requirement to configure both in same router.

Thanks,

[Julio E. Moisa]

Hi

Actually if this router is the CE and you have the control over it only, it should use IPV4 Family address only, VPNV4 is used to create the VPN tunnels between PE routers only or for Inter-AS, the PE is handled by the ISP. 

[sbhadrav@cisco.com]

Each PE router connects to multiple CE devices and receives IPv4 routes from these CEs. The CEs will be from multiple customers and the PE device needs to keep these routes separate so it uses VRFs to achieve this.

But the routes being exchanged between the CE and PE devices are still just IPv4 routes, nothing special, so you configure the peering under an IPv4 address family for that VRF.

Obviously to provide reachability between the customer networks PEs need to exchange these routes between each other. But together with the actual routes they also need to advertise additional information ie. the RD, RT and VPN labels.

The RD is prepended to the IPv4 route to make it unique as well as the RT being included as an extended community and so the routes are no longer normal IPv4 routes, they are now VPNv4 routes and this is why you configure the peering between PEs under a VPNv4 address family.

It's really the difference between the routes you are advertising and to which devices ie. CEs or other PEs.

Note VPNv4 routes are only exchanged between PE routers because only the PE routers need to know about the customer networks..