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Verification Guide: PTL-0030 OSPFv2 Passive Interfaces and Neighbor Control

Assembly details and expected results for OSPFv2 Passive Interfaces and Neighbor Control. It shows the finished configuration, so use it to check your work.

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This document details the complete positive and negative testing matrix for PTL-0030, executed and verified inside Cisco Packet Tracer 9.0.1.

1. Positive Verification (POS)#

POS-01: Transit Link & Local Gateway Ping Reachability#

From Edge-R1, verify direct ICMP echo reachability across the point-to-point transit link to Core-R2:

Edge-R1# ping 10.0.0.2

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.0.0.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 0/0/0 ms

From PC-1 and Server-1, verify local default gateway reachability:

C:\> ping 192.168.10.1
Pinging 192.168.10.1 with 32 bytes of data:
Reply from 192.168.10.1: bytes=32 time<1ms TTL=255
Reply from 192.168.10.1: bytes=32 time<1ms TTL=255

C:\> ping 192.168.20.1
Pinging 192.168.20.1 with 32 bytes of data:
Reply from 192.168.20.1: bytes=32 time<1ms TTL=255
Reply from 192.168.20.1: bytes=32 time<1ms TTL=255
  • Criteria: Transit WAN circuit and local LAN gateways respond with 100% success rate.

Verify that the inter-router OSPF neighbor relationship across GigabitEthernet0/0/1 is established and in FULL state:

On Edge-R1:

Edge-R1# show ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
2.2.2.2           1   FULL/BDR        00:00:38    10.0.0.2        GigabitEthernet0/0/1

On Core-R2:

Core-R2# show ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
1.1.1.1           1   FULL/DR         00:00:37    10.0.0.1        GigabitEthernet0/0/1
  • Criteria: Neighbor table confirms FULL/BDR and FULL/DR states across 10.0.0.0/30. Access LAN interfaces (GigabitEthernet0/0/0) have zero neighbors.

POS-03: Passive Interface Verification on Access Ports#

Inspect OSPF interface details on the edge LAN ports (GigabitEthernet0/0/0) on both routers:

On Edge-R1:

Edge-R1# show ip ospf interface GigabitEthernet0/0/0

GigabitEthernet0/0/0 is up, line protocol is up
  Internet address is 192.168.10.1/24, Area 0
  Process ID 1, Router ID 1.1.1.1, Network Type BROADCAST, Cost: 1
  Transmit Delay is 1 sec, State DR, Priority 1
  Designated Router (ID) 1.1.1.1, Interface address 192.168.10.1
  No backup designated router on this network
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    No Hellos (Passive interface)

On Core-R2:

Core-R2# show ip ospf interface GigabitEthernet0/0/0

GigabitEthernet0/0/0 is up, line protocol is up
  Internet address is 192.168.20.1/24, Area 0
  Process ID 1, Router ID 2.2.2.2, Network Type BROADCAST, Cost: 1
  Transmit Delay is 1 sec, State DR, Priority 1
  Designated Router (ID) 2.2.2.2, Interface address 192.168.20.1
  No backup designated router on this network
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    No Hellos (Passive interface)
  • Criteria: Both routers explicitly report No Hellos (Passive interface) for GigabitEthernet0/0/0.

Inspect GigabitEthernet0/0/1 to verify active Hello packet transmission and timer intervals:

On Edge-R1:

Edge-R1# show ip ospf interface GigabitEthernet0/0/1

GigabitEthernet0/0/1 is up, line protocol is up
  Internet address is 10.0.0.1/30, Area 0
  Process ID 1, Router ID 1.1.1.1, Network Type BROADCAST, Cost: 1
  Transmit Delay is 1 sec, State DR, Priority 1
  Designated Router (ID) 1.1.1.1, Interface address 10.0.0.1
  Backup Designated Router (ID) 2.2.2.2, Interface address 10.0.0.2
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    Hello due in 00:00:08
  Neighbor Count is 1, Adjacent neighbor count is 1
    Adjacent with neighbor 2.2.2.2  (Backup Designated Router)
  Suppress hello for 0 neighbor(s)
  • Criteria: Active timer intervals (Hello 10, Dead 40) and Suppress hello for 0 neighbor(s).

POS-05: Continued Route Propagation for Passive Networks#

Verify that passive LAN subnets continue to be advertised in the Link-State Database and installed into routing tables:

On Edge-R1:

Edge-R1# show ip route ospf
O    192.168.20.0 [110/2] via 10.0.0.2, 00:08:35, GigabitEthernet0/0/1

On Core-R2:

Core-R2# show ip route ospf
O    192.168.10.0 [110/2] via 10.0.0.1, 00:04:34, GigabitEthernet0/0/1
  • Criteria: Both routers have valid OSPF routes (O) to the opposing passive LAN subnets with metric 2 via GigabitEthernet0/0/1.

POS-06: End-to-End Host Reachability#

From PC-1 (192.168.10.10), verify ping and traceroute reachability to Server-1 (192.168.20.10):

C:\> ping 192.168.20.10

Pinging 192.168.20.10 with 32 bytes of data:

Reply from 192.168.20.10: bytes=32 time<1ms TTL=126
Reply from 192.168.20.10: bytes=32 time<1ms TTL=126
Reply from 192.168.20.10: bytes=32 time<1ms TTL=126
Reply from 192.168.20.10: bytes=32 time<1ms TTL=126

Ping statistics for 192.168.20.10:
    Packets: Sent = 4, Received = 4, Lost = 0 (0% loss)

C:\> tracert 192.168.20.10

Tracing route to 192.168.20.10 over a maximum of 30 hops: 

  1   0 ms      1 ms      0 ms      192.168.10.1
  2   0 ms      0 ms      0 ms      10.0.0.2
  3   0 ms      0 ms      0 ms      192.168.20.10

Trace complete.
  • Criteria: 0% packet loss and clean 3-hop forwarding path (192.168.10.1 -> 10.0.0.2 -> 192.168.20.10).

2. Negative Verification (NEG)#

When the transit interface GigabitEthernet0/0/1 is mistakenly configured as passive (passive-interface GigabitEthernet0/0/1), Hello packet exchanges cease across the link. Once the 40-second Dead timer expires, the neighbor adjacency is torn down and all routes learned through Core-R2 are withdrawn from Edge-R1's routing table:

Edge-R1# show ip ospf neighbor
Edge-R1#

Edge-R1# show ip route ospf
Edge-R1#
  • Criteria: Neighbor table and OSPF routing table become empty on Edge-R1.

When passive status is removed from the transit link (no passive-interface GigabitEthernet0/0/1), Hello packets resume immediately. Routers progress through INIT, 2-WAY, EXSTART, EXCHANGE, LOADING, and return to FULL:

00:46:31: %OSPF-5-ADJCHG: Process 1, Nbr 2.2.2.2 on GigabitEthernet0/0/1 from LOADING to FULL, Loading Done

Verify that the remote route is re-installed into Edge-R1's routing table:

Edge-R1# show ip route ospf
O    192.168.20.0 [110/2] via 10.0.0.2, 00:03:57, GigabitEthernet0/0/1
  • Criteria: Adjacency state restores to FULL and routes are restored automatically.

This page is generated from labs/routing/ospfv2-passive-interfaces-and-neighbor-control/verification.md in the repository. Corrections go there.

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