A router ID must be configured, using the router-id router-id router configuration command. The router-id parameter can be any arbitrary 32-bit value, in an IPv4 address format (dotted decimal), but it must be unique on each router.
Use the ipv6 ospf process-id area area-id [instance instance-id] interface configuration command to enable OSPF for IPv6 on an interface. Table 10-4 explains the parameters of this command. In OSPF for IPv6, all addresses on an interface are included by default. There is no limit to the number of ipv6 ospf area commands you can use on the router.
Table 10-4 ipv6 ospf area Command Description
| Parameter | Description |
|---|---|
| process-id | Used for internal identification. The process-id is locally assigned and can be any positive integer. This is the same number used when enabling the OSPF routing process. |
| area-id | Specifies the area that is to be associated with the OSPF interface. |
| instance-id | (Optional) Instance identifier. An OSPF instance (also known as an OSPF process) can be considered a logical router running OSPF in a physical router. Use the instance-id to control selection of other routers as neighboring routers; the router becomes neighbors only with routers that have the same instance ID. |
The OSPF priority, used in DR election, can be changed using the ipv6 ospf priority number-value interface configuration command. The number-value can range from 0 to 255; the default is 1. The router with the higher router priority takes precedence in an election. If there is a tie, the router with the higher router ID takes precedence. A router with a router priority set to zero is ineligible to become the DR or BDR.
The OSPF cost of sending a packet on an interface can be specified using the ipv6 ospf cost interface-cost interface configuration command. The interface-cost can be a value in the range from 1 to 65535. The default cost is related to the bandwidth of the interface, the same as it is for OSPF for IPv4.
Example 10-1 illustrates a basic OSPFv3 configuration example.
Example 10-1 Basic OSPFv3 Configuration
ipv6 unicast-routing ! ipv6 router ospf 1 router-id 10.2.2.2 ! interface FastEthernet0/0 ipv6 address 3FFE:FFFF:1::1/64 ipv6 ospf 1 area 0 ipv6 ospf priority 20 ipv6 ospf cost 20
To consolidate and summarize routes at an area boundary use the area area-id range ipv6-prefix/prefix-length [advertise | not-advertise] [cost cost] IPv6 OSPF router configuration command. Table 10-5 explains the parameters of this command.
Table 10-5 area range Command Description
| Parameter | Description |
|---|---|
| area-id | Identifies the area subject to route summarization. |
| ipv6-prefix/prefix-length | The IPv6 address and prefix length for the range of addresses in the summary route. |
| advertise | (Optional) Sets the address range status to advertise and generates a type 3 summary LSA. |
| not-advertise | (Optional) Sets the address range status to DoNotAdvertise. The type 3 summary LSA is suppressed, and the component networks remain hidden from other networks. |
| cost | (Optional) Metric or cost for this summary route, which is used during OSPF SPF calculation to determine the shortest paths to the destination. The value can be 0 to 16777215. |
The cost of the summarized routes is the highest cost of the routes being summarized. For example, consider the following routes:
OI 2001:0DB8:0:0:7::/64 [110/20] via FE80::A8BB:CCFF:FE00:6F00, FastEthernet0/0 OI 2001:0DB8:0:0:8::/64 [110/100] via FE80::A8BB:CCFF:FE00:6F00, FastEthernet0/0 OI 2001:0DB8:0:0:9::/64 [110/20] via FE80::A8BB:CCFF:FE00:6F00, FastEthernet0/0
If they are summarized, they become one route, as follows:
OI 2001:0DB8::/48 [110/100] via FE80::A8BB:CCFF:FE00:6F00, FastEthernet0/0
Figure 10-17 shows an OSPF network of two routers and two areas, area 0 and area 1. The configuration of Router 1 is shown in Example 10-2, and the configuration of Router 2 is shown in Example 10-3. The interface-specific commands ipv6 ospf 100 area 0 and ipv6 ospf 100 area 1 create the "ipv6 router ospf 100" process dynamically. The area 0 range 2001:410::/32 command in Router 1 summarizes area 0's routes to the 2001:410::/32 route.
OSPFv3 Configuration Example
Example 10-2 Configuration of Router 1 in Figure 10-17
interface Serial0/0/1 ipv6 address 2001:410:FFFF:1::1/64 ipv6 ospf 100 area 0 ! interface Serial0/0/2 ipv6 address 3FFE:B00:FFFF:1::2/64 ipv6 ospf 100 area 1 ! ipv6 router ospf 100 router-id 10.1.1.3 area 0 range 2001:410::/32
Example 10-3 Configuration of Router 2 in Figure 10-17
interface Serial0/0/3 ipv6 address 3FFE:B00:FFFF:1::1/64 ipv6 ospf 100 area 1 ! ipv6 router ospf 100 router-id 10.1.1.4
Verifying IPv6 and OSPFv3
This section explores some of the commands used to verify IPv6 and OSPFv3.
clear ipv6 ospf Command
The clear ipv6 ospf [process-id] {process | force-spf | redistribution | counters [neighbor [neighbor-interface | neighbor-id]]} command triggers SPF recalculation and repopulation of the RIB.
show ipv6 route Command
The show ipv6 route [ipv6-address | ipv6-prefix/prefix-length | protocol | interface-type interface-number] command displays the IPv6 routing table, as illustrated in Example 10-4.
Example 10-4 show ipv6 route Command Output
Router1#show ipv6 route
IPv6 Routing Table - 8 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 2001:410:1:1::/64 [0/0]
via ::, FastEthernet0/0
L 2001:410:1:1:216:46FF:FE50:C470/128 [0/0]
via ::, FastEthernet0/0
O 2001:410:1:2::/64 [110/782]
via FE80::216:46FF:FE10:FC00, Serial0/0/1
C 2001:410:1:3::/64 [0/0]
via ::, Serial0/0/1
L 2001:410:1:3:216:46FF:FE50:C470/128 [0/0]
via ::, Serial0/0/1
O 2001:410:1:4::/64 [110/782]
via FE80::216:46FF:FE10:FDB0, FastEthernet0/0
L FE80::/10 [0/0]
via ::, Null0
L FF00::/8 [0/0]
via ::, Null0
show ipv6 interface Command
The show ipv6 interface [brief] [interface-type interface-number] [prefix] command displays IPv6 information about an interface, as displayed in Example 10-5.
Example 10-5 show ipv6 interface Command Output
Router1#show ipv6 interface FastEthernet0/0 is up, line protocol is up IPv6 is enabled, link-local address is FE80::216:46FF:FE50:C470 No Virtual link-local address(es): Global unicast address(es): 2001:410:1:1:216:46FF:FE50:C470, subnet is 2001:410:1:1::/64 [EUI] Joined group address(es): FF02::1 FF02::2 FF02::1:FF50:C470 MTU is 1500 bytes ICMP error messages limited to one every 100 milliseconds ICMP redirects are enabled ICMP unreachables are sent ND DAD is enabled, number of DAD attempts: 1 ND reachable time is 30000 milliseconds ND advertised reachable time is 0 milliseconds ND advertised retransmit interval is 0 milliseconds ND router advertisements are sent every 200 seconds ND router advertisements live for 1800 seconds ND advertised default router preference is Medium Hosts use stateless autoconfig for addresses. Serial0/0/1 is up, line protocol is up IPv6 is enabled, link-local address is FE80::216:46FF:FE50:C470 No Virtual link-local address(es): Global unicast address(es): 2001:410:1:3:216:46FF:FE50:C470, subnet is 2001:410:1:3::/64 [EUI] Joined group address(es): FF02::1 FF02::2 FF02::1:FF50:C470 MTU is 1500 bytes ICMP error messages limited to one every 100 milliseconds ICMP redirects are enabled ICMP unreachables are sent ND DAD is enabled, number of DAD attempts: 1 ND reachable time is 30000 milliseconds Hosts use stateless autoconfig for addresses.
Example 10-6 illustrates an example of the output of this command with the brief parameter.
Example 10-6 show ipv6 interface brief Command Output
Router3#show ipv6 interface brief FastEthernet0/0 [up/up] FE80::216:46FF:FE10:FC00 2001:410:1:2:216:46FF:FE10:FC00 FastEthernet0/1 [administratively down/down] unassigned Serial0/0/0 [administratively down/down] unassigned Serial0/0/0.1 [administratively down/down] unassigned Serial0/0/0.2 [administratively down/down] unassigned Serial0/0/1 [up/up] FE80::216:46FF:FE10:FC00 2001:410:1:3:216:46FF:FE10:FC00 Loopback0 [up/up] unassigned
show ipv6 ospf interface Command
The show ipv6 ospf [process-id] [area-id] interface [interface] command displays OSPF for IPv6-related interface information, as displayed in Example 10-7.
Example 10-7 show ipv6 ospf interface Command Output
Router1#show ipv6 ospf interface s0/0/1 Serial0/0/1 is up, line protocol is up Link Local Address FE80::213:C3FF:FEDF:5658, Interface ID 7 Area 0, Process ID 100, Instance ID 0, Router ID 10.200.200.11 Network Type POINT_TO_POINT, Cost: 781 Transmit Delay is 1 sec, State POINT_TO_POINT, Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 00:00:05 Index 1/2/2, 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 10.200.200.12 Suppress hello for 0 neighbor(s)
show ipv6 ospf Command
The show ipv6 ospf [process-id] [area-id] command displays general information about the IPv6 OSPF processes. Example 10-8 illustrates example output from this command.
Example 10-8 show ipv6 ospf Command Output
Router7#show ipv6 ospf
Routing Process "ospfv3 1" with ID 172.16.3.3
It is an area border and autonomous system boundary router
Redistributing External Routes from, connected
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 33 msecs
Number of external LSA 3. Checksum Sum 0x12B75
Number of areas in this router is 2. 1 normal 0 stub 1 nssa
Area BACKBONE(0)
Number of interfaces in this area is 1
SPF algorithm executed 23 times
Number of LSA 14. Checksum Sum 0x760AA
Number of DCbitless LSA 0
Number of Indication LSA 0
Number of DoNotAge LSA 0
Flood list length 0
Area 2
Number of interfaces in this area is 1
It is a NSSA area
Perform type-7/type-5 LSA translation
SPF algorithm executed 17 times
Number of LSA 25. Checksum Sum 0xE3BF0
Number of DCbitless LSA 0
Number of Indication LSA 0
Number of DoNotAge LSA 0
Flood list length 0
Table 10-6 provides a description of some of the fields in the output of the show ipv6 ospf command in Example 10-8.
Table 10-6 Description of show ipv6 ospf Command Output in Example 10-8
| Field | Description |
| Routing process "ospfv3 1" with ID 172.16.3.3 | Process ID and OSPF router ID |
| LSA group pacing timer | Configured LSA group pacing timer (in seconds) |
| Interface flood pacing timer | Configured LSA flood pacing timer (in milliseconds [ms]) |
| Retransmission pacing timer | Configured LSA retransmission pacing timer (in ms) |
| Number of areas | Number of areas to which the router is attached |
show ipv6 ospf neighbor Command
The show ipv6 ospf neighbor [detail] command provides information about IPv6 OSPF neighbors. With the detail parameter, detailed information about IPv6 OSPF neighbors is displayed, as illustrated in Example 10-9.
Example 10-9 show ipv6 ospf neighbor detail Command Output
Router1#show ipv6 ospf neighbor detail Neighbor 10.200.200.12 In the area 0 via interface Serial0/0/1 Neighbor: interface-id 7, link-local address FE80::217:95FF:FE42:C330 Neighbor priority is 1, State is FULL, 6 state changes Options is 0x46EAC429 Dead timer due in 00:00:33 Neighbor is up for 00:31:57 Index 1/1/1, retransmission queue length 0, number of retransmission 1 First 0x0(0)/0x0(0)/0x0(0) Next 0x0(0)/0x0(0)/0x0(0) Last retransmission scan length is 1, maximum is 1 Last retransmission scan time is 0 msec, maximum is 0 msec
Table 10-7 provides a description of some of the fields in the output of the show ipv6 ospf neighbor detail command in Example 10-9.