Which protocol is used to exchange VPNv4 routes between PE routers?
- EIGRP with address-family configuration
- OSPF with VRF extensions
- MP-BGP
- LDP
Explanation: According to the sources, MP-BGP (Multi-Protocol BGP) is the specific protocol used to exchange VPNv4 routes between PE routers in an MPLS L3 VPN architecture.
Because customer address spaces may overlap, PE routers use Route Distinguishers (RD) to convert non-unique 32-bit IPv4 prefixes into globally unique 96-bit VPNv4 addresses.
MP-BGP is the only routing protocol capable of scaling to the very large number of routes typically found in provider environments while supporting these extended address families.
These updates, exchanged over MP-IBGP sessions, also carry a VPN label assigned by the egress PE to ensure proper packet forwarding across the provider backbone.
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