OSPF troubleshooting - No route update

R1 and R3 form a neighbor relationship but they are not exchanging route.

R3_CME_2801#sh ip ospf nei

Neighbor ID Pri State Dead Time Address Interface
1.1.1.1 1 FULL/BDR 00:01:41 172.31.77.1 Serial0/3/0
R3_CME_2801#sh ip route ospf

R3_CME_2801#

What is the problem?

Solution: Mismatch in IP OSPF network type -

- make sure you have the same network type on both routers

Sh ip ospf int s0/3/0

- correct the mismatch network
conf t
int s0/3/0
ip ospf network point-to-point





R3_CME_2801#sh ip ospf nei

Neighbor ID Pri State Dead Time Address Interface
1.1.1.1 1 FULL/BDR 00:01:41 172.31.77.1 Serial0/3/0
R3_CME_2801#sh ip route ospf

R3_CME_2801#conf t
Enter configuration commands, one per line. End with CNTL/Z.
R3_CME_2801(config)#int s0/3/0
R3_CME_2801(config-if)#ip ospf net
R3_CME_2801(config-if)#ip ospf network point-to-multipoint
R3_CME_2801(config-if)#
*Jul 10 16:07:56.321: %OSPF-5-ADJCHG: Process 1, Nbr 1.1.1.1 on Serial0/3/0 from FULL to DOWN, Neighbor Down: Interface down or detached
*Jul 10 16:07:56.569: %OSPF-5-ADJCHG: Process 1, Nbr 1.1.1.1 on Serial0/3/0 from LOADING to FULL, Loading Done
R3_CME_2801(config-if)#do sh ip ospf nei

Neighbor ID Pri State Dead Time Address Interface
1.1.1.1 0 FULL/ - 00:01:57 172.31.77.1 Serial0/3/0
R3_CME_2801(config-if)#do sh ip route ospf
172.31.0.0/16 is variably subnetted, 3 subnets, 2 masks
O 172.31.77.2/32 [110/128] via 172.31.77.1, 00:00:27, Serial0/3/0
O 172.31.77.1/32 [110/64] via 172.31.77.1, 00:00:27, Serial0/3/0
10.0.0.0/8 is variably subnetted, 4 subnets, 2 masks
O 10.254.0.0/24 [110/74] via 172.31.77.1, 00:00:27, Serial0/3/0
R3_CME_2801(config-if)#

How to check the ISIS router level-type

The command to check the level-type of an ISIS router is :

sh clns protocol.

You can also check the interface isis level by typing

show clns int s0/1


Ex. I configure router 2 to the default level-1-2
and setup the internal router R6 for level-1 only

R2_2611XM#sh clns pro

IS-IS Router:
System Id: 2222.2222.2222.00 IS-Type: level-1-2
Manual area address(es):
49.0071
Routing for area address(es):
49.0071
Interfaces supported by IS-IS:
Serial0/1 - IP
FastEthernet0/0 - IP
Loopback2 - IP
Redistribute:
static (on by default)
Distance for L2 CLNS routes: 110
RRR level: none
Generate narrow metrics: level-1-2
Accept narrow metrics: level-1-2
Generate wide metrics: none
Accept wide metrics: none



R6_3640#sh clns pro

IS-IS Router:
System Id: 6666.6666.6666.00 IS-Type: level-1
Manual area address(es):
49.0072
Routing for area address(es):
49.0072
Interfaces supported by IS-IS:
Ethernet0/1 - IP
Ethernet0/0 - IP
Loopback6 - IP
Redistribute:
static (on by default)
Distance for L2 CLNS routes: 110
RRR level: none
Generate narrow metrics: level-1-2
Accept narrow metrics: level-1-2
Generate wide metrics: none
Accept wide metrics: none
Serial0/1 is up, line protocol is up
Checksums enabled, MTU 1500, Encapsulation HDLC
ERPDUs enabled, min. interval 10 msec.
CLNS fast switching enabled
CLNS SSE switching disabled
DEC compatibility mode OFF for this interface
Next ESH/ISH in 42 seconds
Routing Protocol: IS-IS
Circuit Type: level-1-2
Interface number 0x2, local circuit ID 0x100
Neighbor System-ID: R3_CME_2801
Level-1 Metric: 10, Priority: 64, Circuit ID: R3_CME_2801.00
Level-1 IPv6 Metric: 10
Number of active level-1 adjacencies: 0
Level-2 Metric: 10, Priority: 64, Circuit ID: R3_CME_2801.00
Level-2 IPv6 Metric: 10
Number of active level-2 adjacencies: 1
Next IS-IS Hello in 673 milliseconds
if state UP