IPv6–OSPVv3

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OSPFv3 is very similar to OSPFv2, configuration wise is almost identical

similar to IPv6 EIGRP the router-id is in 32 bits format, in our setup

we have 3 areas, and because area 34 is not connected to backbone area  we need to configure a virtual link in area 23 to connect area 34 to the backbone

configurations is the same except one caveat that we will try to explore in this post shortly

R1

interface Loopback0
 no ip address
 ipv6 address 2001:1:1::1/64
 ipv6 ospf 1 area 0
!
interface FastEthernet0/0
 ipv6 enable
 ipv6 ospf 1 area 0
!
!
ipv6 router ospf 1
 router-id 1.1.1.1

R2

interface FastEthernet0/0
 ipv6 enable
 ipv6 ospf 1 area 0
!
interface FastEthernet0/1
 ipv6 enable
 ipv6 ospf 1 area 23
!
!
ipv6 router ospf 1
 router-id 2.2.2.2

R3


interface loopback 0
ipv6 address 2001:3:33::3/64
!
interface FastEthernet0/10
 ipv6 enable
 ipv6 ospf 1 area 23
!
interface FastEthernet0/1
 ipv6 enable
 ipv6 ospf 1 area 34
!
!
ipv6 router ospf 1
 router-id 3.3.3.3

R4


interface FastEthernet0/0
 ipv6 enable
 ipv6 ospf 1 area 34
!
!
ipv6 router ospf 1
 router-id 4.4.4.4

We can check check to the OSPFv3 routes on R1 and R3 and see if we can connectivity between the loopback interfaces

R1#show ipv6 route ospf
IPv6 Routing Table - 4 entries
Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP
       U - Per-user Static route, M - MIPv6
       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
       D - EIGRP, EX - EIGRP external
OI  2001:3:33::3/128 [110/2]
     via FE80::C001:7FF:FE10:0, FastEthernet0/0


R3#show ipv route ospf
IPv6 Routing Table - 4 entries
Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP
       U - Per-user Static route, M - MIPv6
       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
       D - EIGRP, EX - EIGRP external
OI  2001:1:1::1/128 [110/2]
     via FE80::C001:7FF:FE10:1, FastEthernet0/0

We can try to ping from R1 to R3, remember we have to source  the ping from loopback interface, all transit links have link-local addresses only and link-local addresses are local to the links they are configured on

R3#ping 2001:1:1::1 source lo0

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:1:1::1, timeout is 2 seconds:
Packet sent with a source address of 2001:3:33::3
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 20/36/60 ms

now we need to configure the virtual link, the configuration is identical to OSPFv2

on R2

R2(config)#ipv6 router ospf 1
R2(config-rtr)#area 23 virtual-link 3.3.3.3

R3

R3(config)#ipv6 router ospf 1
R3(config-rtr)#area 23 virtual-link 2.2.2.2

The moment we configure the two routers, we should should notice the following on R3

R3(config-if)#
*Mar  1 02:23:34.015: %OSPFv3-4-AREA_MISMATCH: Received packet with incorrect area from FE80::C001:7FF:FE10:1, FastEthernet0/0, area 0.0.0.23, packet area 0.0.0.0

which seems like R2 doesn’t have any virtual-links configurations (and we know it does)

if we check the virtual links on both routers

R2

R2(config-if)#do sh ipv6 ospf virtual-link
Virtual Link OSPFv3_VL0 to router 3.3.3.3 is up
  Interface ID 10, IPv6 address 2011:3:33::3
  Run as demand circuit
  DoNotAge LSA allowed.
  Transit area 23, via interface FastEthernet0/1, Cost of using 1
  Transmit Delay is 1 sec, State POINT_TO_POINT,
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 00:00:04

R3

R3#show IPv6 ospf virtual-links
Virtual Link OSPFv3_VL0 to router 2.2.2.2 is down
  Interface ID 11, IPv6 address ::
  Run as demand circuit
  DoNotAge LSA allowed.
  Transit area 23, Cost of using 65535
  Transmit Delay is 1 sec, State DOWN,
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

As we can see, R2 is seeing the virtual-link source from R3 as global address and not the link-local address according to the RFC 2740 this is the only exception when it comes to OSPFv3 neighbors, in general the link local address will be used to form the OSPF ardency but in case of virtual links,  unique local or unique global addresses is required

so we configure a loopback interface on R2 and see if this will fix the issue

R2(config)#interf f0/1
R2(config-if)#ipv6 address fc00:1:23::2/64

The moment you configure the interface loopback on R2 the virtual link should come up

R2#show ipv ospf neighbor

Neighbor ID     Pri   State           Dead Time   Interface ID    Interface
3.3.3.3           1   FULL/  -           -        11              OSPFv3_VL0
1.1.1.1           1   FULL/DR         00:00:37    4               FastEthernet0/0
3.3.3.3           1   FULL/DR         00:00:35    4               FastEthernet0/1

R3#show ipv6 ospf  neighbor

Neighbor ID     Pri   State           Dead Time   Interface ID    Interface
2.2.2.2           1   FULL/  -           -        10              OSPFv3_VL0
2.2.2.2           1   FULL/BDR        00:00:36    5               FastEthernet0/0
4.4.4.4           1   FULL/DR         00:00:33    4               FastEthernet0/1

once thing to notice here. if we check the routes on R3 we will see the loopback interface of R2 has been advertised into OSPF although we haven’t explicitly advertise it  on R2

R3#show ipv route ospf
IPv6 Routing Table - 5 entries
Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP
       U - Per-user Static route, M - MIPv6
       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
       D - EIGRP, EX - EIGRP external
O   2001:1:1::1/128 [110/2]
     via FE80::C001:7FF:FE10:1, FastEthernet0/0
O   FC00:2:2::2/128 [110/1]
     via FE80::C001:7FF:FE10:1, FastEthernet0/0

This is the only global IP address configured on

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