Cisco IOS IPv6 BGP configuration, using link local addresses as transportation

In this example, I am building two external BGP peering relationships. One is going from WAN and the other is going from LAN.

Notes about this example

I just want to save some typing defining neighbors, so I changed all link local addresses to simpler ones. This is not necessary for link local peering to work.

Remember to also define "neighbor update-source”, so IOS could know with which interface to start the BGP’s TCP connection.

 

Key Configuration of R1

interface FastEthernet0/0
 no ip address
 duplex auto
 speed auto
 ipv6 address FE80::3 link-local
 ipv6 enable
!
interface Serial0/0
 no ip address
 ipv6 address FE80::1 link-local
 ipv6 enable
 clock rate 2000000
!
interface FastEthernet0/1
 no ip address
 duplex auto
 speed auto
 ipv6 address 2000:1:1:1::1/64
!
router bgp 65500
 no synchronization
 bgp router-id 1.1.1.1
 bgp log-neighbor-changes
 neighbor FE80::2 remote-as 65400
 neighbor FE80::2 update-source Serial0/0
 neighbor FE80::4 remote-as 65400
 neighbor FE80::4 update-source FastEthernet0/0
 no auto-summary
 !
 address-family ipv6
 neighbor FE80::2 activate
 neighbor FE80::4 activate
 network 2000:1:1:1::/64
 exit-address-family
!

Key Configuration of R2

interface FastEthernet0/0
 no ip address
 duplex auto
 speed auto
 ipv6 address FE80::4 link-local
 ipv6 enable
!
interface Serial0/0
 no ip address
 ipv6 address FE80::2 link-local
 ipv6 enable
 clock rate 2000000
!
interface FastEthernet0/1
 no ip address
 duplex auto
 speed auto
 ipv6 address 2000:2:1:1::1/64
!
router bgp 65400
 no synchronization
 bgp router-id 2.2.2.2
 bgp log-neighbor-changes
 neighbor FE80::1 remote-as 65500
 neighbor FE80::1 update-source Serial0/0
 neighbor FE80::3 remote-as 65500
 neighbor FE80::3 update-source FastEthernet0/0
 no auto-summary
 !
 address-family ipv6
 neighbor FE80::1 activate
 neighbor FE80::3 activate
 network 2000:2:1:1::/64
 exit-address-family
!

BGP Neighbors on R1

R1#show bgp ipv6 unicast summary
BGP router identifier 1.1.1.1, local AS number 65500
BGP table version is 3, main routing table version 3
2 network entries using 298 bytes of memory
3 path entries using 228 bytes of memory
3/2 BGP path/bestpath attribute entries using 372 bytes of memory
1 BGP AS-PATH entries using 24 bytes of memory
0 BGP route-map cache entries using 0 bytes of memory
0 BGP filter-list cache entries using 0 bytes of memory
BGP using 922 total bytes of memory
BGP activity 2/0 prefixes, 3/0 paths, scan interval 60 secs

Neighbor        V    AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
FE80::2         4 65400       7       7        3    0    0 00:02:16        1
FE80::4         4 65400       7       7        3    0    0 00:02:25        1
R1#

 

BGP Table on R1

R1#show bgp ipv6 unicast
BGP table version is 3, local router ID is 1.1.1.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete

   Network          Next Hop            Metric LocPrf Weight Path
*> 2000:1:1:1::/64  ::                       0         32768 i
*  2000:2:1:1::/64  FE80::4                  0             0 65400 i
*>                  FE80::2                  0             0 65400 i
R1#

 

Connectivity Verification

R1#show ipv6 route
IPv6 Routing Table - 5 entries
Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP
       U - Per-user Static route
       I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary
       O - OSPF intra, OI - OSPF inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
       ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2
C   2000:1:1:1::/64 [0/0]
     via ::, FastEthernet0/1
L   2000:1:1:1::1/128 [0/0]
     via ::, FastEthernet0/1
B   2000:2:1:1::/64 [20/0]
     via FE80::2, Serial0/0
L   FE80::/10 [0/0]
     via ::, Null0
L   FF00::/8 [0/0]
     via ::, Null0
R1#
R1#ping 2000:2:1:1::1 source F0/1

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2000:2:1:1::1, timeout is 2 seconds:
Packet sent with a source address of 2000:1:1:1::1
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 16/32/48 ms
R1#