PTL-0031 verification guide

This document details the complete positive and negative testing matrix for PTL-0031, executed and verified inside Cisco Packet Tracer 9.0.1.

1. Negative Verification: Starter Fault Baseline (NEG-01)#

Fault 1: Timer Mismatch on Link 1 (HQ-R1 <-> Branch-R2)#

On HQ-R1, verify that no neighbor is formed across GigabitEthernet0/0/0:

HQ-R1# show ip ospf neighbor
HQ-R1#

Inspect interface timers on both ends of Link 1:

HQ-R1# show ip ospf interface GigabitEthernet0/0/0
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

Branch-R2# show ip ospf interface GigabitEthernet0/0/0
  Timer intervals configured, Hello 5, Dead 20, Wait 20, Retransmit 5

Diagnosis: Branch-R2 has non-default timers (Hello 5, Dead 20) conflicting with HQ-R1's default timers (Hello 10, Dead 40). Because OSPF requires identical Hello and Dead intervals, the neighbor relationship is rejected.

Fault 2: Area ID Mismatch on Link 2 (HQ-R1 <-> Remote-R3)#

Inspect the OSPF area configured on Remote-R3:

Remote-R3# show ip ospf interface GigabitEthernet0/0/0
GigabitEthernet0/0/0 is up, line protocol is up
  Internet address is 10.1.13.2/30, Area 1

Diagnosis: Remote-R3 interface is assigned to Area 1, whereas HQ-R1 GigabitEthernet0/0/1 is in Area 0. OSPF packets arriving with a mismatched Area ID are discarded.

Fault 3: End-to-End Inter-Spoke Communication Failure#

From PC-Branch, verify that communication to Server-Remote fails:

C:\> ping 192.168.3.10

Pinging 192.168.3.10 with 32 bytes of data:

Reply from 192.168.2.1: Destination host unreachable.
Reply from 192.168.2.1: Destination host unreachable.
Reply from 192.168.2.1: Destination host unreachable.
Reply from 192.168.2.1: Destination host unreachable.

Ping statistics for 192.168.3.10:
    Packets: Sent = 4, Received = 0, Lost = 4 (100% loss)

Criteria: All OSPF adjacencies are down and cross-subnet communication returns Destination host unreachable.

2. Positive Verification: Post-Remediation State (POS)#

POS-01: Direct Link Point-to-Point Ping#

From HQ-R1 privileged EXEC mode, verify direct Layer 3 reachability across both transit circuits:

HQ-R1# ping 10.1.12.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.12.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 0/0/0 ms

HQ-R1# ping 10.1.13.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.1.13.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 0/0/0 ms

Criteria: 100% ping success across point-to-point transit circuits.

POS-02: Neighbor Adjacencies on HQ-R1#

Verify that both spoke routers achieve FULL adjacency with HQ-R1:

HQ-R1# show ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
3.3.3.3           1   FULL/DR         00:00:38    10.1.13.2       GigabitEthernet0/0/1
2.2.2.2           1   FULL/DR         00:00:39    10.1.12.2       GigabitEthernet0/0/0

On Branch-R2:

Branch-R2# show ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
1.1.1.1           1   FULL/BDR        00:00:33    10.1.12.1       GigabitEthernet0/0/0

On Remote-R3:

Remote-R3# show ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
1.1.1.1           1   FULL/BDR        00:00:36    10.1.13.1       GigabitEthernet0/0/0

Criteria: Adjacencies on both transit links transition to FULL.

POS-03: Interface Parameter & Timer Synchronization#

Verify synchronized timers on Branch-R2 and corrected Area on Remote-R3:

Branch-R2# show ip ospf interface GigabitEthernet0/0/0
GigabitEthernet0/0/0 is up, line protocol is up
  Internet address is 10.1.12.2/30, Area 0
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

Remote-R3# show ip ospf interface GigabitEthernet0/0/0
GigabitEthernet0/0/0 is up, line protocol is up
  Internet address is 10.1.13.2/30, Area 0
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5

Criteria: Both interfaces operate in Area 0 with Hello 10 and Dead 40 timers.

POS-04: Complete Routing Table Convergence#

Verify learned OSPF routes on each router:

On HQ-R1:

HQ-R1# show ip route ospf
O    192.168.2.0 [110/2] via 10.1.12.2, 00:05:56, GigabitEthernet0/0/0
O    192.168.3.0 [110/2] via 10.1.13.2, 00:05:33, GigabitEthernet0/0/1

On Branch-R2:

Branch-R2# show ip route ospf
     10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
O       10.1.13.0 [110/2] via 10.1.12.1, 00:05:30, GigabitEthernet0/0/0
     192.168.1.0/32 is subnetted, 1 subnets
O       192.168.1.1 [110/2] via 10.1.12.1, 00:05:59, GigabitEthernet0/0/0
O    192.168.3.0 [110/3] via 10.1.12.1, 00:05:30, GigabitEthernet0/0/0

On Remote-R3:

Remote-R3# show ip route ospf
     10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks
O       10.1.12.0 [110/2] via 10.1.13.1, 00:05:35, GigabitEthernet0/0/0
     192.168.1.0/32 is subnetted, 1 subnets
O       192.168.1.1 [110/2] via 10.1.13.1, 00:05:35, GigabitEthernet0/0/0
O    192.168.2.0 [110/3] via 10.1.13.1, 00:05:35, GigabitEthernet0/0/0

Criteria: All routes installed with correct metrics and next-hop gateways.

POS-05: End-to-End Inter-Spoke Host Reachability#

From PC-Branch (192.168.2.10), verify end-to-end communication to Server-Remote (192.168.3.10):

C:\> ping 192.168.3.10

Pinging 192.168.3.10 with 32 bytes of data:

Reply from 192.168.3.10: bytes=32 time<1ms TTL=125
Reply from 192.168.3.10: bytes=32 time<1ms TTL=125
Reply from 192.168.3.10: bytes=32 time<1ms TTL=125
Reply from 192.168.3.10: bytes=32 time<1ms TTL=125

Ping statistics for 192.168.3.10:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss)

C:\> tracert 192.168.3.10

Tracing route to 192.168.3.10 over a maximum of 30 hops: 

  1   0 ms      0 ms      0 ms      192.168.2.1
  2   0 ms      0 ms      0 ms      10.1.12.1
  3   0 ms      0 ms      0 ms      10.1.13.2
  4   0 ms      0 ms      0 ms      192.168.3.10

Trace complete.

Criteria: 0% packet loss and verified 4-hop routing path.

3. Negative Verification: Circuit Failover & Recovery (NEG-02)#

When Branch-R2's transit link GigabitEthernet0/0/0 is administratively shut down (shutdown):

HQ-R1# show ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
3.3.3.3           1   FULL/DR         00:00:32    10.1.13.2       GigabitEthernet0/0/1

Observation: Branch-R2 neighbor drops; Remote-R3 neighbor remains unaffected.

When GigabitEthernet0/0/0 is re-enabled (no shutdown):

HQ-R1# show ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
3.3.3.3           1   FULL/DR         00:00:38    10.1.13.2       GigabitEthernet0/0/1
2.2.2.2           1   FULL/DR         00:00:33    10.1.12.2       GigabitEthernet0/0/0

Observation: Adjacency restores automatically to FULL.

Verification Guide: PTL-0031 OSPFv2 Neighbor Adjacency Troubleshooting