Troubleshooting OSPFv3

Troubleshooting OSPFv3 for IPv6 should be handled in the same way as OSPFv2 for IPv4. The major difference will be the addressing: OSPFv3 uses the link-local addresses as the source and, when sending directly to a neighbor, destination of packets.

Case Study: Frame Relay Mapping

Upon initial configuration of Figure 9-17, Skrewt and Hippogriff are configured with the configurations in Example 9-20 and Example 9-21.

Example 9-20. Skrewt's initial Frame Relay mapping configuration.

interface Serial 0/0  encapsulation frame-relay  ipv6 address 2001:DB8:0:1::1/64  ipv6 ospf network broadcast  ipv6 ospf 1 area 1  frame-relay map ipv6 2001:db8:0:1::2 201 broadcast  frame-relay map ipv6 2001:db8:0:1::3  202 broadcast  frame-relay map ipv6 2001:db8:0:1::4 203 broadcast  ipv6 ospf 1 area 1

Example 9-21. Hippogriff's initial Frame Relay mapping configuration.

interface Serial0/0  no ip address  encapsulation frame-relay  ipv6 address 2001:DB8:0:1::3/64  ipv6 ospf network broadcast  ipv6 ospf 1 area 1  frame-relay map ipv6 2001:DB8:0:1::1 220 broadcast  frame-relay map ipv6 2001:DB8:0:1::2 221 broadcast  frame-relay map ipv6 2001:DB8:0:1::4 223 broadcast

The other routers are configured similarly.

The routers are not becoming adjacent, as shown in Skrewt's OSPFv3 neighbor table in Example 9-22.

Example 9-22. Skrewt is not becoming adjacent to the DR or BDR.

Skrewt#show ipv6 ospf neighbor Neighbor ID     Pri   State          Dead Time    Interface ID    Interface 10.1.3.1          1   EXSTART/DR     00:00:34     4               Serial0/0 10.1.1.23         1   EXSTART/BDR    00:00:31     4               Serial0/0 192.2.2.9         1   2WAY/DROTHER   00:00:36     4               Serial0/0 Skrewt#

Debugging IPv6 OSPF Hellos and adjacencies, Example 9-23, show that Hellos are being received and two-way communication is established. The DR and BDR are elected. Database synchronization is attempted to complete the adjacencies with the DR and BDR. Skrewt attempts to send database description packets (DBD) to the potential DR, but never receives an acknowledgment, although Skrewt does continue to receive Hellos from the potential DR. The neighbor state EXSTART with the DR and BDR indicates that a master/slave relationship is being established and an initial DBD packet has been sent.

Example 9-23. debug ipv6 ospf hello and debug ipv6 ospf adj show Hellos, two-way communication establishment, DR/BDR election, and the sending of DBD packets.

Skrewt#debug ipv6 ospf hello Skrewt#debug ipv6 ospf adj OSPFv3: Rcv hello from 10.1.1.23 area 1 from Serial0/0 FE80::202:FDFF:FE5A:E40 interface ID 4 OSPFv3: 2 Way Communication to 10.1.1.23 on Serial0/0, state 2WAY OSPFv3: Neighbor change Event on interface Serial0/0 OSPFv3: DR/BDR election on Serial0/0 OSPFv3: Elect BDR 10.1.1.23 OSPFv3: Elect DR 10.1.1.23         DR: 10.1.1.23 (Id) BDR: 10.1.1.23 (Id) OSPFv3: Send DBD to 10.1.1.23 on Serial0/0 seq 0xF78 opt 0x0013 flag 0x7 len 28 OSPFv3: Rcv hello from 10.1.3.1 area 1 from Serial0/0 FE80::201:42FF:FE79:E500 interface ID 4 OSPFv3: 2 Way Communication to 10.1.3.1 on Serial0/0, state 2WAY OSPFv3: Neighbor change Event on interface Serial0/0 OSPFv3: DR/BDR election on Serial0/0 OSPFv3: Elect BDR 10.1.1.23 OSPFv3: Elect DR 10.1.3.1         DR: 10.1.3.1 (Id) BDR: 10.1.1.23 (Id) OSPFv3: Send DBD to 10.1.3.1 on Serial0/0 seq 0x1C93 opt 0x0013 flag 0x7 len 28 OSPFv3: Remember old DR 10.1.1.23 (id) OSPFv3: End of hello processing OSPFv3: Send DBD to 10.1.1.23 on Serial0/0 seq 0xF78 opt 0x0013 flag 0x7 len 28 OSPFv3: Retransmitting DBD to 10.1.1.23 on Serial0/0 [1] OSPFv3: Send DBD to 10.1.3.1 on Serial0/0 seq 0x1C93 opt 0x0013 flag 0x7 len 28 OSPFv3: Retransmitting DBD to 10.1.3.1 on Serial0/0 [1] OSPFv3: Send DBD to 10.1.1.23 on Serial0/0 seq 0xF78 opt 0x0013 flag 0x7 len 28 OSPFv3: Retransmitting DBD to 10.1.1.23 on Serial0/0 [2] OSPFv3: Rcv hello from 10.1.1.23 area 1 from Serial0/0 FE80::202:FDFF:FE5A:E40 interface ID 4 OSPFv3: End of hello processing Skrewt#

No acknowledgments are being received. Adding a debug of IPv6 OSPF packets shows additional information about the DBD packets being sent^[3] (Example 9-24).

^[3] Debugging IPv6 packets in a live network is not recommended.

Example 9-24. Adding debug ipv6 ospf packet shows packet encapsulation failures.

Skrewt#debug ipv6 ospf packet OSPFv3: Send DBD to 10.1.1.23 on Serial0/0 seq 0x2422 opt 0x0013 flag 0x7 len 28 IPV6: source FE80::207:85FF:FE6B:EA20 (local)        dest FE80::202:FDFF:FE5A:E40 (Serial0/0)        traffic class 224, flow 0x0, len 68+0, prot 89, hops 1, originating  IPv6: Encapsulation failed OSPFv3: Retransmitting DBD to 10.1.1.23 on Serial0/0 [4]

The DBD packets are not multicast, as Hellos are. They are sent to the IPv6 address of the neighbor router. Recall that OSPFv3 uses the link-local addresses for packet exchange, as can be seen in the output of the IPv6 packet debug. Skrewt does not have a Frame Relay map to FE80::202:FDFF:FE5A:E40 on interface Serial0/0. This is why the encapsulation failed. Frame Relay maps must be configured mapping the link-local address of the neighbor routers to the local DLCI.

To easily obtain the link-local addresses of an IPv6 interface, use show ipv6 interface serial0/0, as shown in Example 9-25 .

Example 9-25. IPv6 information pertinent to an interface can be viewed with the command show ipv6 interface.

Skrewt#show ipv6 interface serial0/0 Serial0/0 is up, line protocol is up   IPv6 is enabled, link-local address is FE80::207:85FF:FE6B:EA20   Global unicast address(es):     2001:DB8:0:1::1, subnet is 2001:DB8:0:1::/64   Joined group address(es):     FF02::1     FF02::2     FF02::5     FF02::1:FF00:1     FF02::1:FF6B:EA20   MTU is 1500 bytes   ICMP error messages limited to one every 100 milliseconds   ICMP redirects are enabled   ND DAD is not supported   ND reachable time is 30000 milliseconds   Hosts use stateless autoconfig for addresses. Skrewt#

Skrewt's and Hippogriff's configurations are changed as displayed in Example 9-26 and Example 9-27.

Example 9-26. Skrewt's Frame Relay mapping statements are changed to the link-local IPv6 addresses.

interface Serial0/0  encapsulation frame-relay  ipv6 address 2001:DB8:0:1::1/64  ipv6 ospf network broadcast  ipv6 ospf 1 area 1  frame-relay map ipv6 fe80::206:28ff:feb6:5bc0 201 broadcast  frame-relay map ipv6 fe80::202:fdff:fe5a:e40 202 broadcast  frame-relay map ipv6 fe80::201:42ff:fe79:e500 203 broadcast

Example 9-27. Hippogriff's Frame Relay mapping statements are changed to the IPv6 link-local addresses.

interface Serial0/0  no ip address  encapsulation frame-relay  ipv6 address 2001:DB8:0:1::3/64  ipv6 ospf network broadcast  ipv6 ospf 1 area 1 frame-relay map ipv6 fe80::207:85ff:fe6b:ea20 220 broadcast frame-relay map ipv6 fe80::206:28ff:feb6:5bc0 221 broadcast frame-relay map ipv6 fe80::201:42ff:fe79:e500 223 broadcast

The IPv6 address that must be mapped to the DLCI is the neighbor's link-local address. Skrewt's correct IPv6 OSPF neighbor table is shown in Example 9-28 .

Example 9-28. After mapping the neighbors' link-local addresses to the local DLCIs, Skrewt is fully adjacent to the DR and BDR.

Skrewt#show ipv6 ospf neighbor Neighbor ID     Pri   State           Dead Time    Interface ID    Interface 192.2.2.9         1   FULL/DR         00:00:32     4               Serial0/0 10.1.1.23         1   2WAY/DROTHER    00:00:37     4               Serial0/0 10.1.3.1          1   FULL/BDR        00:00:38     4               Serial0/0 Skrewt#