I came across a quirk in 12.0(23) where OSPF will permit the installation of equal cost routes (default in this case) from two separate processes & areas. You can see in a couple of places that all interfaces encompassed by the network statements are valid in all OSPF processes. 12.2(12a) does not behave in the same manner. Assuming this was either a 'feature' in 12.0, or perhaps a defect?
In this lab 0.0.0.0/0 is originated from two hops away from the access router (two routers in the core, the distribution layer router are adjacent to the access router).
Is there a way to toggle this behaviour in 12.2+? Comparison of the behaviours below (same router & config, different images).
Thx mosfet
interface Serial0.300 point-to-point description p2p pvc to dist router 1 ospf test bandwidth 2000 ip address 192.168.4.2 255.255.255.240 no ip redirects no ip directed-broadcast ip ospf authentication-key 7 12345678 ip ospf priority 0 frame-relay interface-dlci 300 ! interface Serial0.301 point-to-point description p2p pvc to dist router 2 ospf test bandwidth 2000 ip address 192.168.5.2 255.255.255.240 no ip redirects ip directed-broadcast ip ospf authentication-key 7 12345678 ip ospf priority 0 frame-relay interface-dlci 301 ! router ospf 5 log-adjacency-changes area 192.168.4.0 authentication redistribute connected subnets redistribute static subnets network 192.168.4.0 0.0.0.15 area 192.168.4.0 distribute-list permit-default in ! router ospf 10 log-adjacency-changes area 192.168.5.0 authentication redistribute connected subnets redistribute static subnets network 192.168.5.0 0.0.0.15 area 192.168.5.0 distribute-list permit-default in ! ip access-list standard permit-default permit 0.0.0.0 deny any
router#sh ver Cisco Internetwork Operating System Software IOS (tm) 2500 Software (C2500-I-L), Version 12.0(23), RELEASE SOFTWARE (fc1) ..
router#sh ip ospf neigh
Neighbor ID Pri State Dead Time Address Interface
172.21.254.154 99 FULL/ - 00:00:30 192.168.4.1 Serial0.300 172.21.254.153 99 FULL/ - 00:00:33 192.168.5.1 Serial0.301router#sh ip route ospf O*E1 0.0.0.0/0 [110/76] via 192.168.4.1, 00:02:34, Serial0.300 [110/76] via 192.168.5.1, 00:02:42, Serial0.301
router#sh ip route 0.0.0.0 Routing entry for 0.0.0.0/0, supernet Known via "ospf 5", distance 110, metric 76, candidate default path Tag 5, type extern 1 Redistributing via ospf 5 Last update from 192.168.4.1 on Serial0.300, 00:08:15 ago Routing Descriptor Blocks: * 192.168.4.1, from 172.21.254.156, 00:08:15 ago, via Serial0.300 Route metric is 76, traffic share count is 1 192.168.5.1, from 172.21.254.156, 00:08:24 ago, via Serial0.301 Route metric is 76, traffic share count is 1
router#sh ip ospf 5 nei de Neighbor 172.21.254.154, interface address 192.168.4.1 In the area 192.168.4.0 via interface Serial0.300 Neighbor priority is 99, State is FULL, 6 state changes DR is 0.0.0.0 BDR is 0.0.0.0 Options 66 Dead timer due in 00:00:35 Neighbor 172.21.254.153, interface address 192.168.5.1 In the area 192.168.5.0 via interface Serial0.301 Neighbor priority is 99, State is FULL, 12 state changes DR is 0.0.0.0 BDR is 0.0.0.0 Options 66 Dead timer due in 00:00:34
router#sh ip ospf 10 nei de Neighbor 172.21.254.154, interface address 192.168.4.1 In the area 192.168.4.0 via interface Serial0.300 Neighbor priority is 99, State is FULL, 6 state changes DR is 0.0.0.0 BDR is 0.0.0.0 Options 66 Dead timer due in 00:00:34 Neighbor 172.21.254.153, interface address 192.168.5.1 In the area 192.168.5.0 via interface Serial0.301 Neighbor priority is 99, State is FULL, 12 state changes DR is 0.0.0.0 BDR is 0.0.0.0 Options 66 Dead timer due in 00:00:34
router#sh ip ospf Routing Process "ospf 10" with ID 192.168.5.2 Supports only single TOS(TOS0) routes It is an autonomous system boundary router Redistributing External Routes from, connected, includes subnets in redistribution static, includes subnets in redistribution
Number of areas in this router is 1. 1 normal 0 stub 0 nssa Area 192.168.5.0 Number of interfaces in this area is 1 Area has simple password authentication SPF algorithm executed 5 times
Routing Process "ospf 5" with ID 172.21.254.155 Supports only single TOS(TOS0) routes It is an autonomous system boundary router Redistributing External Routes from, connected, includes subnets in redistribution static, includes subnets in redistribution
Number of areas in this router is 1. 1 normal 0 stub 0 nssa Area 192.168.4.0 Number of interfaces in this area is 1 Area has simple password authentication SPF algorithm executed 4 times
router#ping ip Target IP address: 192.168.2.5 Repeat count [5]: 2 Datagram size [100]: Timeout in seconds [2]: Extended commands [n]: y Source address or interface: Type of service [0]: Set DF bit in IP header? [no]: Validate reply data? [no]: Data pattern [0xABCD]: Loose, Strict, Record, Timestamp, Verbose[none]: R Number of hops [ 9 ]: Loose, Strict, Record, Timestamp, Verbose[RV]: Sweep range of sizes [n]: Type escape sequence to abort. Sending 2, 100-byte ICMP Echos to 192.168.2.5, timeout is 2 seconds: Packet has IP options: Total option bytes= 39, padded length=40 Record route: (0.0.0.0) (0.0.0.0) (0.0.0.0) (0.0.0.0) (0.0.0.0) (0.0.0.0) (0.0.0.0) (0.0.0.0) (0.0.0.0)
Reply to request 0 (8 ms). Received packet has options Total option bytes= 40, padded length=40 Record route: (192.168.4.2) (192.168.2.6) (192.168.2.5) (192.168.2.5) (192.168.4.1) (192.168.4.2) (0.0.0.0) (0.0.0.0) (0.0.0.0) End of list
Reply to request 1 (12 ms). Received packet has options Total option bytes= 40, padded length=40 Record route: (192.168.5.2) (192.168.2.2) (192.168.2.5) (192.168.2.1) (192.168.5.1) (192.168.5.2) (0.0.0.0) (0.0.0.0) (0.0.0.0) End of list
Success rate is 100 percent (2/2), round-trip min/avg/max = 8/10/12 ms