A Sample OSPFv3 Configuration

Before we begin the configuration, we need to enable IPv6 packet forwarding with ipv6 unicast-routing, the IPv6 version of Cisco Express Forwarding (CEF) with ipv6 cef, and the OSPF v3 process with ipv6 router ospf.

R1(config)#ipv6 unicast-routing
R1(config)#ipv6 cef
R1(config)#ipv6 router ospf 1
R2(config)#ipv6 unicast-routing
R2(config)#ipv6 cef
R2(config)#ipv6 router ospf 1

If you don’t have any IPv4 addresses configured on the router, you must configure an OSPF RID with the router-id command.

R1(config)#ipv6 router ospf 1
R2(config)#ipv6 router ospf 1

OSPF v3 interfaces are placed into areas at the interface level.

R1(config-rtr)#int fast 0/1
R1(config-if)#ipv6 ospf 1 ?
area Set the OSPF area ID
R1(config-if)#ipv6 ospf 1 area 0
R2(config-rtr)#int fast 0/1
R2(config-if)#ipv6 ospf 1 area 0

OSPFv3 commands are very similar to OSPFv2:

R2(config-if)#ipv6 ospf ?
<1-65535> Process ID
authentication Enable authentication
cost Interface cost
database-filter Filter OSPF LSA during synchronization and flooding
dead-interval Interval after which a neighbor is declared dead
demand-circuit OSPF demand circuit
flood-reduction OSPF Flood Reduction
hello-interval Time between HELLO packets
mtu-ignore Ignores the MTU in DBD packets
neighbor OSPF neighbor
network Network type
priority Router priority
retransmit-interval Time between retransmitting lost link state advertisements
transmit-delay Link state transmit delay

Debug OSPFv3 Adjacency

*Mar 4 16:13:48.623: %OSPFv3-5-ADJCHG: Process 1, Nbr on FastEthernet0/1 from LOADING to FULL, Loading Done

Verify OSPF v3 adjacencies with show ipv6 ospf neighbor

R2#show ipv6 ospf neighbor
Neighbor ID Pri State Dead Time Interface ID Interface 1 FULL/BDR 00:00:30 10 FastEthernet0/1

To see more details about the neighbor, run show ipv6 ospf neighbor detail. The output is just a little different than OSPF v2.

R2#show ipv6 ospf neighbor detail
In the area 0 via interface FastEthernet0/1
Neighbor: interface-id 10, link-local address FE80::20A:41FF:FE64:31C2
Neighbor priority is 1, State is FULL, 6 state changes
DR is BDR is
Options is 0x84EFB26D
Dead timer due in 00:00:34
Neighbor is up for 00:06:52
Index 1/1/1, retransmission queue length 0, number of retransmission 0
First 0x0(0)/0x0(0)/0x0(0) Next 0x0(0)/0x0(0)/0x0(0)
Last retransmission scan length is 0, maximum is 0
Last retransmission scan time is 0 msec, maximum is 0 msec

show ipv6 ospf interface and show ipv6 ospf database. The first command shows the link-local address of both the local router and the BDR (R1). The second command indicates the use of OSPF v3 in the output almost immediately.

R2#show ipv6 ospf interface fast 0/1
FastEthernet0/1 is up, line protocol is up
Link Local Address FE80::20F:F7FF:FE69:8D21, Interface ID 5
Area 0, Process ID 1, Instance ID 0, Router ID
Network Type BROADCAST, Cost: 1
Transmit Delay is 1 sec, State DR, Priority 1
Designated Router (ID), local address FE80::20F:F7FF:FE69:8D21
Backup Designated router (ID), local address
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Hello due in 00:00:08
Index 1/1/1, flood queue length 0
Next 0x0(0)/0x0(0)/0x0(0)
Last flood scan length is 1, maximum is 4
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 1, Adjacent neighbor count is 1
Adjacent with neighbor (Backup Designated Router)
Suppress hello for 0 neighbor(s)
R2#show ipv6 ospf database
OSPFv3 Router with ID ( (Process ID 1)
Router Link States (Area 0)
ADV Router Age Seq# Fragment ID Link count Bits 415 0x80000003 0 1 None 408 0x80000003 0 1 None

The IPv6 equivalent of OSPF IPv4’s show ip ospf is show ipv6 ospf. This command also indicates the use of OSPF v3.

R2#show ipv6 ospf
Routing Process "ospfv3 1" with ID
SPF schedule delay 5 secs, Hold time between two SPFs 10 secs
Minimum LSA interval 5 secs. Minimum LSA arrival 1 secs
LSA group pacing timer 240 secs
Interface flood pacing timer 33 msecs
Retransmission pacing timer 66 msecs
Number of external LSA 0. Checksum Sum 0x000000
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Reference bandwidth unit is 100 mbps
Number of interfaces in this area is 1
SPF algorithm executed 3 times
Number of LSA 6. Checksum Sum 0x0293F7
Number of DCbitless LSA 0
Number of indication LSA 0
Number of DoNotAge LSA 0
Flood list length 0

Here are some general IPv6 commands and their output you should be familiar with:

R2#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
O 4DDE:EEEE:1::/64 [110/1]
via ::, FastEthernet0/1
C 5DDE:EEEE:1::/64 [0/0]
via ::, FastEthernet0/1
L 5DDE:EEEE:1::1/128 [0/0]
via ::, FastEthernet0/1
L FE80::/10 [0/0]
via ::, Null0
L FF00::/8 [0/0]
via ::, Null0
R2#show ipv6 interface
FastEthernet0/1 is up, line protocol is up
IPv6 is enabled, link-local address is FE80::20F:F7FF:FE69:8D21
Global unicast address(es):
5DDE:EEEE:1::1, subnet is 5DDE:EEEE:1::/64
R2#show ipv6 interface brief
FastEthernet0/0 [administratively down/down]
Serial0/0 [administratively down/down]
FastEthernet0/1 [up/up]
Serial0/1 [administratively down/down]

IPv6: IPv6 Routing + OSPF v3

IPv6 Routing

To go along with the new address types, we have new variations of:

  • RIP for IPv6 – the actual name is RIPng (new generation)
  • EIGRP for IPv6
  • ISIS for IPv6
  • OSPF v3 (Version 3, defined in RFC 2740.)
  • Static routes are still available with IPv6
  • Multiprotocol BGP V4 (MPBGPVer4 or simply MPBGP)

We need to enable a Cisco router’s IPv6 routing capabilities with ipv6 unicast-routing.

R1(config)#ipv6 unicast-routing

OSPF for IPv6 (OSPF v3)

During an IPv4 to IPv6 migration, you may run OSPF v2 and OSPF v3 side by side.

In IPv6, you’re not going to start an OSPF configuration with router ospf. One major difference between v2 and v3 is that v2 is enabled in router config mode and v3 is enabled on a per-interface basis.

This will automatically create a routing process.

R1(config-if)#ipv6 ospf 1 area 0

OSPF v3 is going to use the exact same set of rules to determine the local router’s RID – and v3 is going to use an IPv4 address as the RID

OSPFv2 and V3 differences

  • The basic operational theory of v3 is very similar to that of v2. The Hello packet is still around, as are the LSAs and LSAcks.
  • Stub, total stub, and NSSAs are still around, and the Area 0 rule still exists (as do virtual links).
  • The general rules for neighbor discovery and adjacencies are the same.
  • v3 NBMA configurations require neighbor statements, just like v2.
  • One major difference between the two is that v3 allows a link to be part of multiple OSPF instances, where v2 would allow a link to be part of only one.
  • v3 point-to-point and point-to-multipoint configurations do not elect DRs and BDRs, just like v2.
  • v3 headers are smaller than v2, since v3 headers have no authentication fields.
  • The v2 reserved address is represented in v3 by FF02::5.
  • The v2 reserved address is represented in v3 by FF02::6.
  • We can still use the area range command, and IPv6 does make summarisation more effective – but when you use the area range command in v3, the OSPF cost of that summary is simply the highest of the individual route costs.