The use of Route-Reflectors
Of course you do not want to maintain a full VPNv4-iBGP mesh
Use at least two VPNv4 Route-Reflectors for redundancy reasons
Do not use the IPv4-RRs as VPNv4 Route-Reflectors
- IPv4 Routing instabilities could affect VPN routing
- If PE reloads it would get all 100’000 IPv4 routes first. So it would take several minutes until the VPN routes are restored
- If Route-Reflectors are separated, both feeds are done simultaneously
- So you need at least four Route-Reflectors --> what about core routers?
For better scaling
- Use several VPNv4 RR pairs, each one serving another block of VPNs
- No problem at the PE as the PE only holds routes for connected VPNs
If you use RRs, use global-local-massive-extreme unique RDs
- A different RD per VRF, not per VPN
- otherwise iBGP load-sharing will break
Check the next-hops of the BGP routes you get from the RR :-)