Multiprotocol BGP (MP-BGP) is a BGP extension that enables BGP (Border Gateway Protocol) to transport routing information for different network layers and address families. It can carry Network Layer Reachability Information (NLRI) for IPv4, IPv6, and Multiprotocol Label Switching (MPLS) Layer 3 virtual private networks (L3VPNs).
This extension is backward compatible and is defined in RFC 4670 including the following features:
- Address Family Identifier (AFI)
- Optional and non-transitive attributes: Multiprotocol reachable NLRI and Multiprotocol unreachable NLRI
Optional and non-transitive attribute means that an unrecognizing BGP speaker can ignore it and not advertise to its BGP neighbor.
Multiprotocol reachable NLRI carries the information about the reachable destinations and the next-hop address used to forward packets to these destinations. Multiprotocol unreachable NLRI, on the other hand, is used for withdrawing routes or removing them from advertisements.
MP-BGP extensions add an AFI that identifies the network layer protocol it supports, combined with the Subsequent Address Family Identifier (SAFI) which defines whether the prefixes apply to the same unicast prefixes and multicast routes or to unicast and multicast routes or routing tables.
MP-BGP Configuration
Router1(config)#ipv6 unicast-routing Router1(config)#interface loopback 0 Router1(config-if)#ipv6 enable Router1(config-if)#ipv6 address 2001:DB8::1/128 Router1(config)#interface GigabitEthernet0/0 Router1(config-if)#ipv6 enable Router1(config-if)#ipv6 address 2001:DB8:0:10::1/64 Router1(config)#router bgp 1 Router1(config-router)#bgp log-neighbor-changes Router1(config-router)#neighbor 2001:db8:0:10::2 remote-as 65200 Router1(config-router)#address-family ipv4 Router1(config-router-af)#no neighbor 2001:db8:0:10::2 activate Router1(config-router-af)#exit-address-family Router1(config-router)#address-family ipv6 Router1(config-router-af)#neighbor 2001:db8:0:10::2 activate Router1(config-router-af)#network 2001:db8::1/128 Router1(config-router-af)#exit-address-family
Router2(config)#ipv6 unicast-routing Router2(config)#interface loopback 0 Router2(config-if)#ipv6 enable Router2(config-if)#ipv6 address 2001:DB8::2/128 Router2(config)#interface GigabitEthernet0/0 Router2(config-if)#ipv6 enable Router2(config-if)#ipv6 address 2001:DB8:0:10::2/64 Router2(config)#router bgp 2 Router2(config-router)#bgp log-neighbor-changes Router2(config-router)#neighbor 2001:db8:0:10::1 remote-as 65100 Router2(config-router)#address-family ipv4 Router2(config-router-af)#no neighbor 2001:db8:0:10::1 activate Router2(config-router-af)#exit-address-family Router2(config-router)#address-family ipv6 Router2(config-router-af)#neighbor 2001:db8:0:10::1 activate Router2(config-router-af)#network 2001:db8::2/128 Router2(config-router-af)#exit-address-family
Verification
Router1#show ipv6 route bgp IPv6 Routing Table - default - 7 entries Codes: C - Connected, L - Local, S - Static, U - Per-user Static route B - BGP, HA - Home Agent, MR - Mobile Router, R - RIP I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary D - EIGRP, EX - EIGRP external, NM - NEMO, ND - Neighbor Discovery l - LISP O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2 ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2 B 2001:DB8::2/128 [20/0] via FE80::217:5AFF:FEED:7AF0, GigabitEthernet0/0
Router1#show ipv6 route bgp IPv6 Routing Table - default - 7 entries Codes: C - Connected, L - Local, S - Static, U - Per-user Static route B - BGP, HA - Home Agent, MR - Mobile Router, R - RIP I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary D - EIGRP, EX - EIGRP external, NM - NEMO, ND - Neighbor Discovery l - LISP O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2 ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2 B 2001:DB8::1/128 [20/0] via FE80::217:5AFF:FEED:7AF0, GigabitEthernet0/0
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