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The contents of this document are subject to revision without notice due to continued progress in methodology, design and manufacturing. Ericsson shall have no liability for any error or damage of any kind resulting from the use of this document. | |||
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1 Troubleshooting General OSPF Issues
1.1 Sample OSPF Topology
Use the following sample Open Shortest Path First (OSPF) topology and configuration as a guide to troubleshooting general OSPF issues. The configuration and sample output in this section match the sample topology. For specific OSPF issues, see Section 2.
Figure 1 Sample OSPF Topology
- Note:
- Troubleshooting OPSFv3 is beyond the scope of this document.
1.2 Sample OSPF Configuration
The following are sample OSPF configurations on the jazz and rock1200 routers, which match the sample topology in Section 1.1.
The more complex configuration is on router rock1200. The other routers simply have a context with an OSPF instance configured for area 0. This setup produces all possible LSAs.
Routers two, three, four, and five are contexts on router rock1200, not standalone SmartEdge® routers.
1.2.1 jazz Router Configuration
The SmartEdge OS supports multiple OSPF processes on the SmartEdge router. The OSPF configuration on the jazz router shows that the OSPF process running on that router is process 22. The SmartEdge OS also supports multiple OSPF processes on the same router, which can help in the redistribution of routes between OSPF processes and keep routes from different OSPF processes separate.
Building configuration... Current configuration: ! context jazz ! no ip domain-lookup ! router ospf 22 fast-convergence router-id 22.0.0.0 area 0.0.0.0 interface to-rock1200 interface to-five ! ! ! ! ! ! End [local]Redback#show config Building configuration... Current configuration: ! ! Configuration last changed by user 'test' at Tue Aug 31 15:17:58 2010 ! ! ! ! ! ! service multiple-contexts ! ! ! ! ! ! ! ! ! ! ! ! ! dpi access-list list1 ! ! ! ! ! context local ! no ip domain-lookup ! interface mgmt ip address 10.18.17.102/24 ! interface pim1 logging console ! ! ! administrator test encrypted 1 $1$........$kvQfdsjs0ACFMeDHQ7n/o. privilege start 15 ! ! ip route 10.0.0.0/11 10.18.17.254 ip route 155.53.0.0/16 10.18.17.254 ! ! ! context jazz ! no ip domain-lookup ! interface to-five ip address 15.15.15.1/24 ! interface to-rock1200 ip address 11.11.11.2/24 no logging console ! router ospf 22 fast-convergence router-id 22.0.0.0 area 0.0.0.0 interface to-rock1200 interface to-five ! ! ! ! ! ! ! card ge-5-port 6 ! port ethernet 6/1 no shutdown encapsulation dot1q dot1q pvc 1 bind interface to-rock1200 jazz dot1q pvc 2 bind interface to-five jazz ! ! port ethernet 7/1 ! XCRP management ports on slot 7 and 8 are configured through 7/1 no shutdown bind interface mgmt local ! card ch-ds3-3-port 10 ! card ge-2-ort 14 ! port ethernet 14/1 no shutdown encapsulation dot1q ! timeout session idle 999 ! no service console-break ! service crash-dump-dram ! no service auto-system-recovery ! end
1.2.2 rock1200 Router Configuration
context rock1200 ! no ip domain-lookup ! interface to-jazz ip address 11.11.11.1/24 ! interface to-three ip address 13.13.13.1/24 ! interface to-two ip address 12.12.12.1/24 no logging console ! router ospf 1 fast-convergence router-id 11.0.0.0 area 0.0.0.0 virtual-link 3.0.0.4 0.0.0.4 interface to-jazz area 2.0.0.0 area-type nssa interface to-two area 3.0.0.4 interface to-three ! ! ! ! ! context two ! no ip domain-lookup ! interface to-rock1200 ip address 12.12.12.2/24 no logging console ! router ospf 2 fast-convergence router-id 0.0.0.2 area 2.0.0.0 area-type nssa interface to-rock1200 redistribute static ! ip route 88.88.88.88/32 null0 ! ! ! ! ! context three ! no ip domain-lookup ! interface to-four ip address 34.34.34.1/24 ! interface to-rock1200 ip address 13.13.13.2/24 no logging console ! ip route 99.99.99.99/32 null0 ! ! ! ! ! context four ! no ip domain-lookup ! interface to-five p2p ip address 45.45.45.1/24 ! interface to-three ip address 34.34.34.2/24 no logging console ! router ospf 4 fast-convergence router-id 0.0.0.4 area 0.0.0.0 interface to-five virtual-link 3.0.0.4 11.0.0.0 area 3.0.0.4 interface to-three ! ! ! ! context five ! no ip domain-lookup ! interface to-four p2p ip address 45.45.45.2/24 ! interface to-jazz ip address 15.15.15.2/24 no logging console ! router ospf 5 fast-convergence router-id 0.0.0.5 area 0.0.0.0 interface to-four interface to-jazz ! ! card ge-20-port 9 ! port ethernet 9/1 no shutdown encapsulation dot1q dot1q pvc 1 bind interface to-jazz rock1200 dot1q pvc 2 bind interface to-jazz five ! port ethernet 9/2 no shutdown encapsulation dot1q dot1q pvc 1 bind interface to-two rock1200 dot1q pvc 2 bind interface to-three rock1200 dot1q pvc 3 bind interface to-four three dot1q pvc 4 bind interface to-five four ! port ethernet 9/3 no shutdown encapsulation dot1q dot1q pvc 1 bind interface to-rock1200 two dot1q pvc 2 bind interface to-rock1200 three dot1q pvc 3 bind interface to-three four dot1q pvc 4 bind interface to-four five ! End
1.3 Tasks for Troubleshooting General OSPF Issues
Use the following table as a guide to troubleshooting general OSPF issues. More information about each step is provided in subsequent sections.
|
Task |
Command |
Notes |
Checked? |
|---|---|---|---|
|
show context all show ospf instance-id show process ospf |
|
||
|
show port show port counters ping |
|
||
|
show ip interface brief
|
|
||
|
ping |
Verify that links between routers are operational. |
||
|
show configuration ospf show ospf global |
|
||
|
show ospf neighbor
|
|
||
|
show ospf database |
This database includes information about the network topology for this area. All the routers in this area should have the same database. Make sure SPF has the required LSAs. |
||
|
show ospf route
|
|
||
|
show ip route
|
|
||
|
show ospf statistics [instance-id| Interface] [detail] |
Verify the OSPF traffic information. |
||
|
show ospf spf |
Display a history of the SPF calculation results. |
||
|
show log | grep ospf |
Filter the log for entries relating to OSPF. You must enable the log-neighbor-up-down command to view OSPF logs. |
||
|
monitor ospf interface
|
|
||
|
debug ospf packet errors |
Check for MTU, area ID, authentication, and interface issues. Note: Risk of performance loss. Enabling the generation of debug messages can severely affect system performance. To reduce the risk, exercise caution when enabling the generation of debug messages on a production system. |
1.4 Step 1: Navigate to the Correct Context
Run the show context all command to display all the contexts on the router, and then navigate to the context you want to troubleshoot—in this case, rock1200.
[local]rock1200#show context all Context Name Context ID VPN-RD Description ------------------------------------------------------------------------------ local 0x40080001 rock1200 0x40080082 two 0x40080083 three 0x40080084 four 0x40080085 five 0x40080086 [local]rock1200#context rock1200 [rock1200]rock1200#
Run the show ospf [instance-id] command to display high-level information for all OSPF instances or for a specific instance.
[rock1200]rock1200#show ospf --- OSPF Instance 1/Router ID 11.0.0.0 --- Intra-Distance : 110 Inter-Distance : 110 Ext-Distance : 110 Type of Service : TOS-Type0 Area Border Rtr : Yes AS Boundary Rtr : Yes Auto-Cost : Yes Flood Queued : 0 SPF Delay : 5 SPF Holdtime : 10 Full SPF Count : 12 Incr SPF Count : 0 Full SPF Vers : 12 Incr SPF Vers : 0 SPF LastCompute : 01:42:27 Nbrs Adjacent : 3 Nbrs Exchanging : 0 Global Exchg Max: 300 Redist Metric : Unspecified Redist Queued : 0 Redist Count : 0 Redist Quantum : 2000 Stub Rtr Config : None Stub Rtr Delay : 0 Stub Router : No BGP Converged : No MPLS Traffic Eng: No MPLS Shortcuts : No Demand DC Clear : 0 Demand Indicate : 0 Demand DoNotAge : 6 Helper Neighbors: 0 Graceful Restart: No Restart Status : No Restart Graceful Helper : Yes Strict Check : No Fast Convergence: Yes Fast LSA Orig : No Area List (3 total): 0.0.0.0 2.0.0.0 3.0.0.4 [rock1200]rock1200#
Run the show process ospf command to check for process restarts and uptime.
[rock1200]rock1200#show process ospf NAME PID SPAWN MEMORY TIME %CPU STATE UP/DOWN ospf 2038 1 7472K 00:00:15.61 0.00% run 01:59:38
1.5 Step 2: Verify Port Status
Run the show port command to verify that the ports are up. To see "Admin" and "Line" states, run the show port detail command.
Before you check the status of a port, make sure that you understand the differences between the Admin state and the Line state:
- Admin state—Refers whether the port has been brought
up (by using the no shutdown command) or is down (by
using the shutdown command). If the Admin state is shut down, the port is down.
Recommended Action: Run the no shutdown command on the port to bring up the port.
- Line state—Refers to the physical state of the port.
Recommended Action: When the Line state is down, use the checklist in Table 2.
|
# |
Line State Troubleshooting Checklist |
Checked? |
|---|---|---|
|
1 |
Is the cable correctly connecting the two ports or nodes? In some cases, you might have ports looped together externally to connect different interfaces within separate contexts and share routing information between the two contexts through OSPF. In this case, check if both ports and their corresponding interfaces are up. |
|
|
2 |
Is there a fault in the cable? |
|
|
3 |
Are you using the right type of cable? For example, with Ethernet, are you using a cross-over cable instead of a straight cable? |
|
|
4 |
When the cable is connected to two nodes, is there a fault in one of the nodes? |
|
|
5 |
Is the card with a fiber port receiving light? Is the LOS LED in the port on? |
|
|
6 |
If you are using fiber optics, are you using the appropriate fiber type (for example, multimode or single mode) ? |
|
|
7 |
Is the other end port shut down? |
|
|
8 |
Is there a link speed or duplex setting mismatch? |
|
|
9 |
Is the SmartEdge router gigabit Ethernet port connected to an FE port? The SmartEdge router gigabit Ethernet traffic cards do not support FE speeds. |
|
|
10 |
Are the fibers correctly connected? |
|
|
11 |
Does the circuit configuration match? |
|
|
12 |
Is the line card configured correctly? |
If the Admin state is Down, the Line state is always down. For the port to be Up, the Admin state and Line state must both be Up. To see "Admin" and "Line" states, run the show port detail command. The show port command always returns real-time results. To see results in real time, use the detail keyword. You can use the detail or live parameters when verifying port counters or circuit counters. For detailed information about each field , see the Command List.
Use the following table to determine whether a port is Up or Down.
|
Admin State (Configuration) |
Line State (Physical) |
Result |
|---|---|---|
|
Up |
Down |
Down |
|
Up |
Up |
Up |
|
Down |
Up |
Down |
|
Down |
Down |
Down |
In the following example, the status of the Ethernet ports is Up.
[rock1200]rock1200#show port Slot/Port:Ch:SubCh Type State 7/1 ethernet Up 9/1 ethernet Up 9/2 ethernet Up 9/3 ethernet Up 9/4 ethernet Up [rock1200]rock1200#
In the following example, the status of the Ethernet port is Down. Although the Ethernet port is in a no shutdown state and the Admin state is Up, the cable has been unplugged from the Ethernet port 8/1 and, as a result, the Line state (the physical state) is Down.
[rock1200]rock1200#show port 9/1 detail ethernet 9/1 state is Up Description : Line state : Down Admin state : UpLink Dampening : disabled Undampened line state : Down Dampening Count : 0 Encapsulation : dot1q MTU size : 1500 Bytes NAS Port Type : NAS-Port-Id : MAC address : 00:30:88:11:d1:8d Media type : 1000Base-LX Auto-negotiation : on state: fail Flc negotiated set : tx state: tx℞ force : disabled state: inactive Flow control : rx state: n/a Speed : 1 Gbps Duplex mode : full Link Distance : 15000 meters Loopback : off SFP Transceiver Status Wavelength : 1310.00 nm Diag Monitor : Yes Tx Fault : No Fault Rx Fault : No Fault Tx Pwr measured[dbm] : -11.90 Rx Pwr measured[dbm] : -6.72 Temperature : 49 C Vcc Measured : 3.27 V Active Alarms : Link down
Each line card collects Layer 1, 2, and 3 statistics. Counters are updated every 60 seconds, unless you specify the live parameter. To check port counters, generate traffic on the port, and then run the show port counters command several times to determine if traffic is increasing on the port. For detailed information about each field displayed, see the Command List.
[rock1200]rock1200#show port counters Port Type 7/1 ethernet packets sent : 19293 bytes sent : 1999412 packets recvd : 42333 bytes recvd : 3148785 9/1 ethernet packets sent : 448760 bytes sent : 41552940 packets recvd : 479000 bytes recvd : 44527492 send packet rate : 0.58 send bit rate : 422.60 recv packet rate : 0.60 recv bit rate : 461.52 rate refresh interval : 60 seconds 9/2 ethernet packets sent : 889361 bytes sent : 82364298 packets recvd : 953289 bytes recvd : 88298488 send packet rate : 1.15 send bit rate : 856.66 recv packet rate : 1.13 recv bit rate : 851.59 rate refresh interval : 60 seconds 9/3 ethernet packets sent : 889415 bytes sent : 82332018 packets recvd : 954644 bytes recvd : 88457916 send packet rate : 1.13 send bit rate : 851.60 recv packet rate : 1.15 recv bit rate : 856.66 rate refresh interval : 60 seconds 9/4 ethernet packets sent : 0 bytes sent : 0 packets recvd : 0 bytes recvd : 0 send packet rate : 0.00 send bit rate : 0.00 recv packet rate : 0.00 recv bit rate : 0.00 rate refresh interval : 60 seconds [rock1200]rock1200#
1.6 Step 3: Verify Interfaces
1.6.1 Verify All Interfaces
Run the show ip interface brief command (in the local context) to check if the interfaces are enabled and Up. This command displays information about all interfaces, associated addresses, states, and bindings, including the interface bound to the Ethernet management port on the controller card.
An interface can be in any of the following states:
- Unbound—The reasons why the interface might be
unbound are that the interface is not currently bound to any port
or circuit. The binding is not valid. The VLANs need to match.
- Note:
- In some cases, an interface can have an Unbound state and still be valid; for example, multibind interfaces where no active PPPoE or CLIPS sessions are active.
- Bound—The interface is bound to at least one port or circuit; however, none of the bound circuits are up. Therefore, the interface is not up. The binding is valid. The state Bound is expected behavior for multibind interfaces where there are no active subscribers.
- Up—At least one of the bound circuits is in the up state; therefore, the interface is also up and traffic can be sent over the interface. The binding is valid.
If the interfaces are not Up, check the configuration and make sure you have enabled the interface. Both endpoints must have the same interface type; for example, point-to-multipoint or NBMA.
When OSPF passive mode is enabled, OSPF continues to advertise the interface IP subnet, but it does not send OSPF packets and drops all received OSPF packets. Enable OSPF passive mode by using the passive command for either of the following:
- An individual OSPF interface
- All interfaces within a defined OSPF area
When the interface is defined as passive, no adjacency will be formed and, as result, you will not see this interface in the show ospf neighbor command output. For detailed information about each field displayed, see the Command List.
[local]rock1200#show ip interface brief Tue Dec 14 07:04:50 2010 Name Address MTU State Bindings loopback 10.10.10.2/32 1500 Up (Loopback) mgmt 10.18.17.103/24 1500 Up ethernet 7/1 to-jazz 1.1.1.2/24 1500 Up ethernet 9/1 [local]rock1200#
1.6.2 Verify OSPF Interfaces
Run the show ospf interface command to verify that the OSPF interfaces are Up.
Use the detail keyword to display detailed information about the interface.
|
if-name |
Optional. Interface name. Displays information only for the specified interface. |
|
ip-address |
Optional. Name of a particular interface. |
|
detail |
Optional. Displays detailed OSPF interface information. |
Run the show ospf interface output to display summary information about all configured OSPF interfaces in context rock1200:
[rock1200]rock1200#show ospf interface --- OSPF Interfaces for Instance 1/Router ID 11.0.0.0 --- Addr Len NetworkType Cost Priority State Area 0.0.0.4 0 virtual 2 1 P2P 0.0.0.0 11.11.11.1 24 broadcast 1 1 BDR 0.0.0.0 12.12.12.1 24 broadcast 1 1 BDR 2.0.0.0 13.13.13.1 24 broadcast 1 1 DR 3.0.0.4 [rock1200]rock1200#
Run the show ospf interface command with the argument if-name to display information about a specific OSPF interface, to-jazz:
[rock1200]rock1200#show ospf interface to-jazz --- OSPF Interface 11.11.11.1 Area 0.0.0.0 Instance 1 --- Network Type : broadcast Mask : 255.255.255.0 Cost : 1 Logical Intf : to-jazz MTU : 1500 Physical Intf : ethernet 9/1 State : BDR Priority : 1 Hello Interval : 10 Dead Interval : 40 Transmit Delay : 1 Retransmit Int : 5 DR Router ID : 22.0.0.0 DR IP Address : 11.11.11.2 BDR Router ID : 11.0.0.0 BDR IP Address : 11.11.11.1 Ack Queued : 1 Flood Queued : 0 Ack Delay : 2 Authentication : None LSA Count : 0 LSA Checksum : 0 Demand Circuit : No Flood Reduction: No Neighbor Count : 1 Neighbor List (1 Adjacent): 22.0.0.0 [rock1200]rock1200#
Run the show ospf interface detail command to view detailed information about your OSPF interfaces:
[rock1200]rock1200#show ospf interface detail --- OSPF Interface 0.0.0.4 Area 0.0.0.0 Instance 1 --- Network Type : virtual Mask : 0.0.0.0 Endpoint Router: 0.0.0.4 Transit Area : 3.0.0.4 Cost : 2 Logical Intf : to-three MTU : 1500 Physical Intf : ethernet 9/2 State : P2P Priority : N/A Hello Interval : 10 Dead Interval : 40 Transmit Delay : 1 Retransmit Int : 5 Ack Queued : 0 Flood Queued : 0 Ack Delay : 2 Authentication : None LSA Count : 0 LSA Checksum : 0 Demand Circuit : Yes Flood Reduction: Yes Suppress Allow : Yes Suppress Active: Yes Neighbor Count : 1 Neighbor List (1 Adjacent): 0.0.0.4 --- OSPF Interface 11.11.11.1 Area 0.0.0.0 Instance 1 --- Network Type : broadcast Mask : 255.255.255.0 Cost : 1 Logical Intf : to-jazz MTU : 1500 Physical Intf : ethernet 9/1 State : DR Priority : 1 Hello Interval : 10 Dead Interval : 40 Transmit Delay : 1 Retransmit Int : 5 DR Router ID : 11.0.0.0 DR IP Address : 11.11.11.1 BDR Router ID : 0.0.0.0 BDR IP Address : 0.0.0.0 Ack Queued : 0 Flood Queued : 0 Ack Delay : 2 Authentication : None LSA Count : 0 LSA Checksum : 0 Demand Circuit : No Flood Reduction: No Neighbor Count : 0 --- OSPF Interface 12.12.12.1 Area 2.0.0.0 Instance 1 --- Network Type : broadcast Mask : 255.255.255.0 Cost : 1 Logical Intf : to-two MTU : 1500 Physical Intf : ethernet 9/2 State : DR Priority : 1 Hello Interval : 10 Dead Interval : 40 Transmit Delay : 1 Retransmit Int : 5 DR Router ID : 11.0.0.0 DR IP Address : 12.12.12.1 BDR Router ID : 0.0.0.2 BDR IP Address : 12.12.12.2 Ack Queued : 0 Flood Queued : 0 Ack Delay : 2 Authentication : None LSA Count : 0 LSA Checksum : 0 Demand Circuit : No Flood Reduction: No Neighbor Count : 1 Neighbor List (1 Adjacent): 0.0.0.2 --- OSPF Interface 13.13.13.1 Area 3.0.0.4 Instance 1 --- Network Type : broadcast Mask : 255.255.255.0 Cost : 1 Logical Intf : to-three MTU : 1500 Physical Intf : ethernet 9/2 State : DR Priority : 1 Hello Interval : 10 Dead Interval : 40 Transmit Delay : 1 Retransmit Int : 5 DR Router ID : 11.0.0.0 DR IP Address : 13.13.13.1 BDR Router ID : 0.0.0.3 BDR IP Address : 13.13.13.2 Ack Queued : 0 Flood Queued : 0 Ack Delay : 2 Authentication : None LSA Count : 0 LSA Checksum : 0 Demand Circuit : No Flood Reduction: No Neighbor Count : 1 Neighbor List (1 Adjacent): 0.0.0.3 :
1.7 Step 4: Verify Connectivity
Run the ping and traceroute commands to verify that links between routers are operational. Use the ping command to check directly connected interfaces and virtual links. Use the traceroute command to check for virtual links.
On router rock1200, the following example successfully pings and traces the routes of router four (context four) with the address 34.34.34.2:
[rock1200]rock1200#ping 34.34.34.2 PING 34.34.34.2 (34.34.34.2): source 13.13.13.1, 36 data bytes, timeout is 1 second !!!!! ----34.34.34.2 PING Statistics---- 5 packets transmitted, 5 packets received, 0.0% packet loss round-trip min/avg/max/stddev = 1.784/2.000/2.258/0.172 ms [rock1200]rock1200# [rock1200]rock1200#traceroute 34.34.34.2 se_traceroute to 34.34.34.2 (34.34.34.2), 30 hops max, 40 byte packets 1 13.13.13.2 (13.13.13.2) 3.178 ms 1.889 ms 1.988 ms 2 34.34.34.2 (34.34.34.2) 3.914 ms 3.700 ms 2.975 ms [rock1200]rock1200#
1.8 Step 5: Check the OSPF Configuration and Instances
Run the show configuration ospf command to verify the OSPF configuration in specific context. Because you are running OSPF in multiple contexts, run the show configuration ospf all-contexts command to verify the OSPF configuration in all contexts (instead of just running it from one context).
When examining a router configuration, use the following OSPF configuration checklist as a guide to isolate the fault.
|
# |
Task |
Checked |
|
1 |
Do all interfaces have the correct addresses and masks? |
|
|
2 |
Are the interfaces enabled on the local router? |
|
|
3 |
Is OSPF configured on all neighboring interfaces, and do the OSPF parameters on the neighboring interfaces match? |
|
|
4 |
Are all the OSPF interfaces configured in the correct areas? |
|
|
5 |
Does the authentication type match on local and remote routers? |
|
|
6 |
Are both sides configured with the correct authentication key? |
|
|
7 |
Are both sides configured with matching area IDs? Neighboring interfaces must be in the same area to establish neighborhship. |
|
|
8 |
Did you check for any stub, transit, or NSSA mismatch? |
|
|
9 |
Do both endpoints must have the same interface type? |
Run the show ospf global command to view multiple routing OSPF instances in different routing contexts.
The following output displays the OSPF configuration in the context rock1200:
[rock1200]rock1200#show configuration ospf Building configuration... Current configuration: ! ! ! context rock1200 ! router ospf 1 fast-convergence router-id 11.0.0.0 area 0.0.0.0 virtual-link 3.0.0.4 0.0.0.4 interface to-jazz area 2.0.0.0 area-type nssa interface to-two area 3.0.0.4 interface to-three ! ! ** End Context ** ! end [rock1200]rock1200#
The following output displays the OSPF configurations in all contexts:
[local]rock1200#show configuration ospf all-contexts Building configuration... Current configuration: ! ! Configuration last changed by user 'test' at Tue Dec 14 06:41:04 2010 ! context local ! router ospf 1 fast-convergence area 0.0.0.0 interface loopback interface to-jazz ! ! ** End Context ** ! ! ! context rock1200 ! router ospf 1 fast-convergence router-id 11.0.0.0 area 0.0.0.0 virtual-link 3.0.0.4 0.0.0.4 interface to-jazz area 2.0.0.0 area-type nssa interface to-two area 3.0.0.4 interface to-three ! ! ** End Context ** ! ! ! context two ! router ospf 2 fast-convergence router-id 0.0.0.2 area 2.0.0.0 area-type nssa interface to-rock1200 redistribute static ! ! ** End Context ** ! ! ! context three ! router ospf 3 fast-convergence router-id 0.0.0.3 area 3.0.0.4 interface to-four interface to-rock1200 redistribute static ! ! ** End Context ** ! ! ! context four ! router ospf 4 fast-convergence router-id 0.0.0.4 area 0.0.0.0 interface to-five virtual-link 3.0.0.4 11.0.0.0 area 3.0.0.4 interface to-three ! ! ** End Context ** ! ! ! context five ! router ospf 5 fast-convergence router-id 0.0.0.5 area 0.0.0.0 interface to-four interface to-jazz ! ! ** End Context ** ! ! ! context rock1200 ! router ospf 1 fast-convergence log-neighbor-up-down ! ! ** End Context ** ! end [local]rock1200#
The following output displays the number of OSPF instances configured on the SmartEdge router in the local context:
[local]rock1200#show ospf global --- OSPF Global Information --- Instance Count : 6 Equal-Cost Paths : 8 Sham Link Count : 0 Schedule Delay usecs: 1000 Neighbors Exchanging: 0 Exchanging Nbr Max : 300 Restarted : No Restart reason : Unknown High Res Timers : Yes Receive Cfg EOF : Yes Shared Mem. Cleanup : No [local]rock1200#
1.9 Step 6: Check OSPF Adjacency
When OSPF adjacency is formed, the router state changes as follows before it becomes fully adjacent with its neighbor:
- Down—No information has been received from the neighbor.
- Attempt—Attempt is valid for neighbors on NBMA network; the neighbor is being contacted, but no information has been received.
- Init—A Hello packet has been received from the neighbor, but the router is not listed in that Hello packet.
- 2-Way—The 2-way state indicates that the router has identified its own router ID in the Neighbor field of the neighbor’s Hello packet. Receiving a database descriptor packet from a neighbor in the init state also causes a transition to the 2-way state. Receiving a hello with an OSPF neighbor in 2-way state is not a concern in broadcast multiaccess networks at the DR.. Other routers in these networks cannot progress beyond the 2-way state; in these networks, they achieve Full state only with Designated Router (DR) and Backup Designated Router (BDR). The adjacency must pass through 2-way state before proceeding to a Full state. Failure to pass through the 2-way state indicates there might be an error in the database exchange.
- ExStart—The routers and their Designated Router (DR) and Backup Designated Router (BDR) establish a master-slave relationship and choose the initial sequence number for adjacency formation.
- Exchange—OSPF routers exchange database descriptor (DD) packets. After the packet header, DD packets contain Link-state advertisement (LSA) headers only. They provide a summary of the sender's database contents to the receiving router.
- Loading—Routers send link-state request packets. During the database exchange, if a router receives a more recent or missing link-state advertisement (LSA), it requests that LSA by sending a link-state request packet.
- Full—Indicates that routers are fully adjacent with each other. All the router and network LSAs are exchanged, and the router databases are fully synchronized. Full is the normal state for an OSPF router. A router is stuck in another state indicates problems in forming adjacencies but not necessarily for broadcast and NBMA networks.
The following flowchart describes the general process for troubleshooting OSPF neighbor state issues.
Figure 2 Troubleshooting OSPF Neighbor States
Before OSPF routers can exchange routing information, they must establish a neighborship.
Run the show ospf neighbor [neighbor-id | interface [ip-addr | if-name]] [detail] command to verify that every router has established neighborship.
|
Syntax |
Description |
|
neighbor-id |
Optional. ID of the neighbor for which information is displayed. |
|
interface |
Optional. Displays information for the specified neighbor interface. |
|
ip-addr |
Optional. IP address of the interface. |
|
if-name |
Optional. Interface name. |
|
detail |
Optional. Displays detailed information. |
1.9.1 Verify OSPF Neigbhorship
Run the show ospf neighbor command to verify that you have established adjacency with your neighbors. The configuration on both endpoints (the interface type; for example, point-to-multipoint or P2P) must match; otherwise, you cannot form an adjacency. This is a common issue.
Values other than two-way and full can indicate the following problems:
- Physical issues—If the MTU is too large, the routers
attached to the link cannot negotiate the same MTU on the link, and
an adjacency cannot form.
For example, when the OSPF neighbor state is stuck in an init state, the router can receive packets from the neighbor but not transmit packets to the neighbor, resulting in a one-way link.
- Configuration Issues—If routers attached to the link cannot negotiate the link Area ID, the link Hello protocol timers, the link authentication type, or keys, adjacencies cannot form.
When examining adjacencies, use the following OSPF adjacency checklist to isolate the fault. For more information about how to troubleshoot OSPF adjacencies, see Section 2.
|
# |
Task |
Checked |
|
1 |
Are Hello packets being sent from both neighbors? |
|
|
2 |
Are the dead timers set the same between neighbors? |
|
|
3 |
Are the interfaces configured on the same subnet (that is, do the address or mask pairs belong to the same subnet)? |
|
|
4 |
If authentication is being used, is the authentication type the same between neighbors?
|
|
|
5 |
If the adjacency is across a virtual link, is the link configured within a stub area? |
|
|
6 |
Do neighbor MTUs match? |
|
|
7 |
Are router IDs unique within the entire internetwork? If not, no neighborship will form. |
|
|
8 |
Did you verify that the interface is not defined as passive in OSPF? If it is, no adjacency is formed. Recommended Action: Remove the passive command from the OSPF configuration. |
|
|
9 |
Is the network type the same for neighboring interfaces? |
The output of the show ospf neighbor command from rock1200 indicates it has formed neighborships with routers two, three, four, and jazz as expected (has a Full state).
Full state indicates that routers are fully adjacent with each other. All the router and network LSAs are exchanged and the routers databases are fully synchronized. Full is the normal state for an OSPF router. 2-way is a valid state for a neighbor on a broadcast or NBMA network when neither neighbor is Designated Router (DR) or Backup Designated Router (BDR). If a router is stuck in another state, there might be problems in forming adjacencies.
For more information about how to troubleshoot OSPF neighborhship, see Section 2.
[rock1200]rock1200#show ospf neighbor --- OSPF Neighbors for Instance 1/Router ID 11.0.0.0 --- NeighborID NeighborAddress Pri State DR-State IntfAddress TimeLeft 0.0.0.4 34.34.34.2 1 Full Other 0.0.0.4 0 22.0.0.0 11.11.11.2 1 Full DR 11.11.11.1 35 0.0.0.2 12.12.12.2 1 Full DR 12.12.12.1 39 0.0.0.3 13.13.13.2 1 Full BDR 13.13.13.1 40 [rock1200]rock1200#
You can run the show ospf neighbor interface if-name command to display OSPF adjacency information for a specific interface.
The following output shows an adjacency that is Up on router rock1200 on interface to-jazz.
[rock1200]rock1200#show ospf neighbor interface to-jazz --- OSPF Neighbors for Instance 1/Router ID 11.0.0.0 --- NeighborID NeighborAddress Pri State DR-State IntfAddress TimeLeft 22.0.0.0 11.11.11.2 1 Full DR 11.11.11.1 34
1.9.2 Display Detailed OSPF Neighbor Information
Run the show ospf neighbor detail command to display detailed OSPF neighbor information. In the following output, all the expected neighbors are Up (in a Full state) and are working correctly. Full state indicates that routers are fully adjacent with each other.
[rock1200]rock1200#show ospf neighbor detail --- OSPF Neighbor 0.0.0.4 Area 0.0.0.0 Instance 1 --- Address : 34.34.34.2 Interface Addr : 0.0.0.4 State : Full DR State : Other Cost : 2 DR Priority : 1 DR IP Address : 0.0.0.0 BDR IP Address : 0.0.0.0 LSA Request : 0 LSA Retrans : 0 DB Exchange : 0 Time Till Dead : 0 Hello Options : E,DC DD Options : E,DC,O --- OSPF Neighbor 22.0.0.0 Area 0.0.0.0 Instance 1 --- Address : 11.11.11.2 Interface Addr : 11.11.11.1 State : Full DR State : DR Cost : 1 DR Priority : 1 DR IP Address : 11.11.11.2 BDR IP Address : 11.11.11.1 LSA Request : 0 LSA Retrans : 0 DB Exchange : 0 Time Till Dead : 32 Hello Options : E DD Options : E,O --- OSPF Neighbor 0.0.0.2 Area 2.0.0.0 Instance 1 --- Address : 12.12.12.2 Interface Addr : 12.12.12.1 State : Full DR State : DR Cost : 1 DR Priority : 1 DR IP Address : 12.12.12.2 BDR IP Address : 12.12.12.1 LSA Request : 0 LSA Retrans : 0 DB Exchange : 0 Time Till Dead : 40 Hello Options : NP DD Options : NP,O --- OSPF Neighbor 0.0.0.3 Area 3.0.0.4 Instance 1 --- Address : 13.13.13.2 Interface Addr : 13.13.13.1 State : Full DR State : BDR Cost : 1 DR Priority : 1 DR IP Address : 13.13.13.1 BDR IP Address : 13.13.13.2 LSA Request : 0 LSA Retrans : 0 DB Exchange : 0 Time Till Dead : 31 Hello Options : E DD Options : E,O [rock1200]rock1200#
1.10 Step 7: Verify LSAs in the OSPF Database
Because OSPF is a link-state protocol, the link-state database should be the same for any router in the same area, except during brief periods of convergence. Each router has a link-state database with information about each router in the network and uses this information to build a network topology and calculate the best routes. All routers within the same area must have the same database content to help them identify the best routes. The LSA advertisement changes frequently, indicated by the fact that the sequence number is significantly higher than that of other LSAs.
Only the links that are appropriate for forwarding are included in the database. OSPF routers become fully adjacent with routers with which they have successfully completed the database synchronization process, during which OSPF routers exchange link-state information to populate their databases with the same information. An incomplete database results in an incomplete network view and, as a result, routing problems.
Use the OSPF database to draw a complete map of the network and observe the state of all the routers in the network. Examine the various LSAs; for example, if a link is unstable, the LSA advertising will change frequently, indicated by a sequence number that is significantly higher than that of other LSAs.
You can determine which parts of the network are changing the most by checking the LSA sequence numbers and the age of the LSA in the LS Age field. If the same LSA remains in the database, the LSA age increases. If LSAs are updated frequenly, the age remains low. The LSAge does not need to be the same in both router databases, but the other identifying elements of the LSA header should be the same.
The most common reasons for OSPF to not share the database information about a specific link include:
- The OSPF neighbor is not advertising routes.
- The OSPF neighbor (ABR) is not advertising the summary route.
- The OSPF neighbor is not advertising external routes.
- The OSPF neighbor is not advertising the default route.
To determine whether routers have a synchronized OSPF database, run the show ospf database command and compare the results of the shared areas:
- Verify that the summaries of their LSA checksum fields are equal.
- Determine that the two routers have the same number of LSAs (in the same area) in their link state databases.
If you have routing problems, make sure your interfaces are correctly configured.
|
Field |
Description |
|---|---|
|
instance-id |
Optional. OSPF instance ID. The range of values is 1 to 65,535. |
|
area-id |
Optional. Area ID. The range of values is 0 to 4,294,967,295.. Either a single integer or IP address format. |
|
ip-addr |
Optional. Area IP address. Either a single integer or IP address format. |
|
databases-summary-network detail |
Displays a count, grouped by type, of OSPF LSAs |
|
database router |
Displays information about OSPF router LSAs. |
|
database network |
Display information about OSPF network LSAs |
When checking an area-wide issue, consider the following issues:
- Is the ABR correctly configured?
- Are all the routers configured for the same area type?
- When summarization is enabled, is it correctly configured?
Two common problems are related to summarization in OSPF:
- A router is not summarizing interarea routes.
- A router is not summarizing external routes.
If you suspect that the link-state databases are corrupt or that the databases are not synchronized:
- Run the show ospf database database-summary command to verify the number of LSAs in each router database. For a given area, the number of each LSA type should be the same in all routers.
- Run the show ospf database command and verify that each LSA checksum is the same in a given area in every router database.
OSPF sends LSAs to all routers within the area. The LSA contains information about attached interfaces, link metrics and other variables.
In the following example, router rock1200 and two are synchronized (all routers contain the same database) in area 2.0.0.0. On context rock1200, the LSAs highlighted correctly match the LSAs in context two (router two).
To determine if you have the latest version of the LSAs, check the sequence number associated with the LSA in the show ospf database output. On each node, verify that each node OSPF database has synchronized this information to ensure that each router has the same view of your network.
[local]rock1200#context rock1200
[rock1200]rock1200#show ospf database
--- OSPF Link State Database for Instance 1/Router ID 11.0.0.0 ---
Router Link State Advertisements (Area 0.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
0.0.0.4 0.0.0.4 800001c1 f5c5 E,DC 60 820
0.0.0.5 0.0.0.5 800001bf 5480 E,DC 60 92
11.0.0.0 11.0.0.0 800001c4 1eb2 E,DC 48 358
22.0.0.0 22.0.0.0 800001c2 ace4 E,DC 48 1703
Network Link State Advertisements (Area 0.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
11.11.11.2 22.0.0.0 800001b9 d64f E,DC 32 217
15.15.15.1 22.0.0.0 800001ba 1b05 E,DC 32 1177
Summary Network Link State Advertisements (Area 0.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
12.12.12.0 11.0.0.0 800001bb 64b E,DC 28 358
13.13.13.0 0.0.0.4 800001bb 371d E,DC 28 250
13.13.13.0 11.0.0.0 800001bd dd6e E,DC 28 328
34.34.34.0 0.0.0.4 800001bb 36df E,DC 28 305
34.34.34.0 11.0.0.0 800001bb f419 E,DC 28 23
Summary AS Border Router Link State Advertisements (Area 0.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
0.0.0.3 0.0.0.4 800001ba d8a0 E,DC 28 510
0.0.0.3 11.0.0.0 800001b8 91e2 E,DC 28 1338
11.0.0.0 0.0.0.4 800001b9 73fd E,DC 28 1345
Router Link State Advertisements (Area 2.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
0.0.0.2 0.0.0.2 800001bd fd1f NP,DC 36 1225
11.0.0.0 11.0.0.0 800001bf 1cec NP,DC 36 1408
Network Link State Advertisements (Area 2.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
12.12.12.2 0.0.0.2 800001ba 8ab9 NP,DC 32 1355
Summary Network Link State Advertisements (Area 2.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
11.11.11.0 11.0.0.0 800001b9 d37c NP,DC 28 583
13.13.13.0 11.0.0.0 800001bb 87c0 NP,DC 28 1003
15.15.15.0 11.0.0.0 800001bb 49f7 NP,DC 28 483
34.34.34.0 11.0.0.0 800001bb 9a6d NP,DC 28 358
45.45.45.0 11.0.0.0 800001ba 19cd NP,DC 28 1138
NSSA Link State Advertisements (Area 2.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
0.0.0.0 11.0.0.0 800001bb 31b9 DC 36 898
88.88.88.88 0.0.0.2 800001ba f570 NP,DC 36 845
Router Link State Advertisements (Area 3.0.0.4)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
0.0.0.3 0.0.0.3 800001c3 aa8c E,DC 48 1356
0.0.0.4 0.0.0.4 800001be 6235 E,DC 36 1664
11.0.0.0 11.0.0.0 800001c1 b053 E,DC 36 203
Network Link State Advertisements (Area 3.0.0.4)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
13.13.13.1 11.0.0.0 800001bb 5be1 E,DC 32 888
34.34.34.1 0.0.0.3 800001ba 9677 E,DC 32 176
Summary Network Link State Advertisements (Area 3.0.0.4)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
11.11.11.0 0.0.0.4 800001b9 8dcd E,DC 28 2019
11.11.11.0 11.0.0.0 800001b8 3027 E,DC 28 1478
12.12.12.0 0.0.0.4 800001bc 63f1 E,DC 28 1659
12.12.12.0 11.0.0.0 800001ba 84a E,DC 28 298
15.15.15.0 0.0.0.4 800001bb ee5f E,DC 28 1234
15.15.15.0 11.0.0.0 800001ba a5a2 E,DC 28 1828
45.45.45.0 0.0.0.4 800001bb a84c E,DC 28 689
45.45.45.0 11.0.0.0 800001bc 6f7b E,DC 28 303
External Link State Advertisements
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
88.88.88.88 11.0.0.0 800001b8 194e E,DC 36 1523
99.99.99.99 0.0.0.3 800001b9 9ec9 E,DC 36 381
--- OSPF Link State Database for Instance 1/Router ID 11.0.0.0 ---
Router Link State Advertisements (Area 0.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
0.0.0.4 0.0.0.4 800001c1 f5c5 E,DC 60 859
0.0.0.5 0.0.0.5 800001bf 5480 E,DC 60 131
11.0.0.0 11.0.0.0 800001c4 1eb2 E,DC 48 397
22.0.0.0 22.0.0.0 800001c2 ace4 E,DC 48 1742
Network Link State Advertisements (Area 0.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
11.11.11.2 22.0.0.0 800001b9 d64f E,DC 32 256
15.15.15.1 22.0.0.0 800001ba 1b05 E,DC 32 1216
Summary Network Link State Advertisements (Area 0.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
12.12.12.0 11.0.0.0 800001bb 64b E,DC 28 397
13.13.13.0 0.0.0.4 800001bb 371d E,DC 28 289
13.13.13.0 11.0.0.0 800001bd dd6e E,DC 28 367
34.34.34.0 0.0.0.4 800001bb 36df E,DC 28 344
34.34.34.0 11.0.0.0 800001bb f419 E,DC 28 62
Summary AS Border Router Link State Advertisements (Area 0.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
0.0.0.3 0.0.0.4 800001ba d8a0 E,DC 28 549
0.0.0.3 11.0.0.0 800001b8 91e2 E,DC 28 1377
11.0.0.0 0.0.0.4 800001b9 73fd E,DC 28 1384
<< The LSAs highlighted in bold correctly match the LSAs in context two.
Router Link State Advertisements (Area 2.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
0.0.0.2 0.0.0.2 800001bd fd1f NP,DC 36 1264
11.0.0.0 11.0.0.0 800001bf 1cec NP,DC 36 1447
Network Link State Advertisements (Area 2.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
12.12.12.2 0.0.0.2 800001ba 8ab9 NP,DC 32 1394
Summary Network Link State Advertisements (Area 2.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
11.11.11.0 11.0.0.0 800001b9 d37c NP,DC 28 622
13.13.13.0 11.0.0.0 800001bb 87c0 NP,DC 28 1042
15.15.15.0 11.0.0.0 800001bb 49f7 NP,DC 28 522
34.34.34.0 11.0.0.0 800001bb 9a6d NP,DC 28 397
45.45.45.0 11.0.0.0 800001ba 19cd NP,DC 28 1177
NSSA Link State Advertisements (Area 2.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
0.0.0.0 11.0.0.0 800001bb 31b9 DC 36 937
88.88.88.88 0.0.0.2 800001ba f570 NP,DC 36 884
Router Link State Advertisements (Area 3.0.0.4)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
0.0.0.3 0.0.0.3 800001c3 aa8c E,DC 48 1395
0.0.0.4 0.0.0.4 800001be 6235 E,DC 36 1703
11.0.0.0 11.0.0.0 800001c1 b053 E,DC 36 242
Network Link State Advertisements (Area 3.0.0.4)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
13.13.13.1 11.0.0.0 800001bb 5be1 E,DC 32 927
34.34.34.1 0.0.0.3 800001ba 9677 E,DC 32 215
Summary Network Link State Advertisements (Area 3.0.0.4)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
11.11.11.0 0.0.0.4 800001b9 8dcd E,DC 28 2058
11.11.11.0 11.0.0.0 800001b8 3027 E,DC 28 1517
12.12.12.0 0.0.0.4 800001bc 63f1 E,DC 28 1698
12.12.12.0 11.0.0.0 800001ba 84a E,DC 28 337
15.15.15.0 0.0.0.4 800001bb ee5f E,DC 28 1273
15.15.15.0 11.0.0.0 800001ba a5a2 E,DC 28 1867
45.45.45.0 0.0.0.4 800001bb a84c E,DC 28 728
45.45.45.0 11.0.0.0 800001bc 6f7b E,DC 28 342
External Link State Advertisements
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
88.88.88.88 11.0.0.0 800001b8 194e E,DC 36 1562
99.99.99.99 0.0.0.3 800001b9 9ec9 E,DC 36 420
[rock1200]rock1200#][rock1200]rock1200#context two
[two]rock1200#show ospf database
--- OSPF Link State Database for Instance 2/Router ID 0.0.0.2 ---
Router Link State Advertisements (Area 2.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
0.0.0.2 0.0.0.2 80000266 a9c9 NP,DC 36 1667
11.0.0.0 11.0.0.0 80000268 c797 NP,DC 36 1472
Network Link State Advertisements (Area 2.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
12.12.12.2 0.0.0.2 80000264 3465 NP,DC 32 262
Summary Network Link State Advertisements (Area 2.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
11.11.11.0 11.0.0.0 80000261 8126 NP,DC 28 1202
13.13.13.0 11.0.0.0 80000264 336b NP,DC 28 822
15.15.15.0 11.0.0.0 80000263 f6a1 NP,DC 28 847
34.34.34.0 11.0.0.0 80000263 4817 NP,DC 28 1292
45.45.45.0 11.0.0.0 80000263 c478 NP,DC 28 102
NSSA Link State Advertisements (Area 2.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
0.0.0.0 11.0.0.0 80000264 dc64 DC 36 1847
88.88.88.88 0.0.0.2 80000262 a31a NP,DC 36 1092
[two]rock1200#
1.11 Step 8: Check OSPF Routes
1.11.1 Verify OSPF Routes in the Control Plane
Run the show ospf route command to verify OSPF routes in the control plane. Use the summary keyword to display a summary of OSPF routes.
[rock1200]rock1200#show ospf route
--- OSPF Routes for Instance 1/Router ID 11.0.0.0 ---
Destination Type Dest-Type/Proto Cost Nhops Nhop
11.11.11.0/24 Intra Net 1 1 to-jazz
12.12.12.0/24 Intra Net 1 1 to-two
13.13.13.0/24 Intra Net 1 1 to-three
15.15.15.0/24 Intra Net 2 1 11.11.11.2
34.34.34.0/24 Intra Net 2 1 13.13.13.2
45.45.45.0/24 Intra Net 3 2 11.11.11.2
13.13.13.2
88.88.88.88/32 NSSA T2 Net 0 1 12.12.12.2
<--Redistributed routes that came from the NSSA area (area 2)
99.99.99.99/32 EXT T2 Net 0 1 13.13.13.2
[rock1200]rock1200#
[rock1200]rock1200#show ospf route summary
--- OSPF Route Summary for Instance 1/Router ID 11.0.0.0 ---
Total routes : 8 Redistributed routes : 0
Intra-area routes : 6 Inter-area routes : 0
External type 1 routes: 0 External type 2 routes: 1
NSSA type 1 routes : 0 NSSA type 2 routes : 1
[rock1200]rock1200#
1.11.2 Verify OSPF Route Entries in the RIB
Run the show ip route ospf command to view all OSPF route entries in the RIB table (both active and standby paths).
[rock1200]rock1200#show ip route ospf
Codes: C - connected, S - static, S dv - dvsr, R - RIP, e B - EBGP, i B - IBGP
A,H - derived hidden
O - OSPF, O3 - OSPFv3, IA - OSPF(v3) inter-area,
N1 - OSPF(v3) NSSA external type 1, N2 - OSPF(v3) NSSA external type 2
E1 - OSPF(v3) external type 1, E2 - OSPF(v3) external type 2
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, N - NAT
IPH - IP Host, SUB A - Subscriber address, SUB S - Subscriber static
SUB P - AAA downloaded aggregate subscriber routes
SUB N - Subscriber ND, SUB D - Subscriber DHCP-PD
M F - Mobile Sub Foreign Agent, M H - Mobile Sub Home Agent
M G - Mobile Sub GTP
A - Derived Default, MeH - Media Nexthop
> - Active Route, * - LSP
Type Network Next Hop Dist Metric UpTime Interface
O 11.11.11.0/24 11.11.11.1 110 1 to-jazz
O 12.12.12.0/24 12.12.12.1 110 1 to-two
O 13.13.13.0/24 13.13.13.1 110 1 to-three
> O 15.15.15.0/24 11.11.11.2 110 2 1w2d to-jazz
> O 34.34.34.0/24 13.13.13.2 110 2 1w2d to-three
> O 45.45.45.0/24 11.11.11.2 110 3 1w2d to-jazz
> 13.13.13.2 to-three
> O N2 88.88.88.88/32 12.12.12.2 110 0 1w2d to-two
> O E2 99.99.99.99/32 13.13.13.2 110 0 1w2d to-three
[rock1200]rock1200#
1.11.3 View a Specific OSPF Route Entry
Run the show ospf route address command to view a specific OSPF route path—in this case, 11.11.11.0, and the next hop taken in the OSPF route table through the to-jazz interface.
[rock1200]rock1200#show ospf route 11.11.11.0 OSPF longest prefix route lookup: Instance ID : 1 Router ID : 11.0.0.0 Destination : 11.11.11.0/24 Type : Intra Dest-type : Net Cost : 1 SPF Version : 35 Distance : 110 Area : 0.0.0.0 Back Link Data : 11.11.11.1 LSDB Type : Net LSDB ID : 11.11.11.2 LSDB Adv Router: 22.0.0.0 Next Hop Count : 1 Next Hop 1 Intf: to-jazz Next Hop 1 Addr: 11.11.11.1 Route Flags : interface, intra-transit-net [rock1200]rock1200#
1.12 Step 9: Verify IP Routes
This section describes the various commands to verify the route tables and OSPF route information in them. These commands are context-specific.
1.12.1 Verify the Active Routes in the RIB Table
Run the show ip route command to view the active (best) routes in the RIB. To view a specific address, specify the network prefix by using the ip-addr/prefix-length construct.
The following output shows an OSPF entry identified by the type value O.
The network 15.15.15.0/24 is reachable by the next hop 11.11.11.2 through the to_jazz interface.
The network 34.34.34.0/24 is reachable by the next hop 13.13.13.2 through the to_three interface.
The network 45.45.45.0/24 is reachable using two next hops, either 11.11.11.2 or 13.13.13.2.
[rock1200]rock1200#show ip route
Codes: C - connected, S - static, S dv - dvsr, R - RIP, e B - EBGP, i B - IBGP
O - OSPF, O3 - OSPFv3, IA - OSPF(v3) inter-area,
N1 - OSPF(v3) NSSA external type 1, N2 - OSPF(v3) NSSA external type 2
E1 - OSPF(v3) external type 1, E2 - OSPF(v3) external type 2
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, N - NAT
IPH - IP Host, SUB A - Subscriber address, SUB S - Subscriber static
SUB P - AAA downloaded aggregate subscriber routes
SUB N - Subscriber ND, SUB D - Subscriber DHCP-PD
M F - Mobile Sub Foreign Agent, M H - Mobile Sub Home Agent
M G - Mobile Sub GTP
A - Derived Default, MeH - Media Nexthop
> - Active Route, * - LSP
Type Network Next Hop Dist Metric UpTime Interface
> C 11.11.11.0/24 0 0 1w2d to-jazz
> C 12.12.12.0/24 0 0 1w3d to-two
> C 13.13.13.0/24 0 0 1w3d to-three
> O 15.15.15.0/24 11.11.11.2 110 2 1w2d to-jazz
> O 34.34.34.0/24 13.13.13.2 110 2 1w2d to-three
> O 45.45.45.0/24 11.11.11.2 110 3 1w2d to-jazz
> 13.13.13.2 to-three
[rock1200]rock1200#
[rock1200]rock1200#show ip route 15.15.15.0
Longest match Routing entry for 15.15.15.0/32 is 15.15.15.0/24 , version 16
Route Uptime 1w5d
Paths: total 1, best path count 1
Route has been downloaded to following slots
X-EP-NAME, 09/0
Path information :
Active path :
Known via ospf 1, type-OSPF intra area, distance 110, metric 2,
Tag 0, Next-hop 11.11.11.2, NH-ID 0x34500018, Adj ID: 0x8000021, Interface
to-jazz
Circuit 9/1:1023:63/1/2/9
[rock1200]rock1200#
To check redistribution problems for a static route:
- Run the show ip route static command to view static routes.
- Run the show ospf route command and verify that the static routes have been redistributed into OSPF.
1.12.2 Verify All Routes Stored in the RIB
Run the show ip route all command to view all the routes stored in the RIB from all routing protocols.
The following example displays the routes stored in the RIB on router rock1200.
[rock1200]rock1200#show ip route all
Codes: C - connected, S - static, S dv - dvsr, R - RIP, e B - EBGP, i B - IBGP
A,H - derived hidden
O - OSPF, O3 - OSPFv3, IA - OSPF(v3) inter-area,
N1 - OSPF(v3) NSSA external type 1, N2 - OSPF(v3) NSSA external type 2
E1 - OSPF(v3) external type 1, E2 - OSPF(v3) external type 2
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, N - NAT
IPH - IP Host, SUB A - Subscriber address, SUB S - Subscriber static
SUB P - AAA downloaded aggregate subscriber routes
SUB N - Subscriber ND, SUB D - Subscriber DHCP-PD
M F - Mobile Sub Foreign Agent, M H - Mobile Sub Home Agent
M G - Mobile Sub GTP
A - Derived Default, MeH - Media Nexthop
> - Active Route, * - LSP
Type Network Next Hop Dist Metric UpTime Interface
> C 11.11.11.0/24 0 0 1w2d to-jazz
O 11.11.11.0/24 11.11.11.1 110 1 to-jazz
> C H 11.11.11.0/32 0 0 1w2d to-jazz
> C H 11.11.11.1/32 0 0 1w2d to-jazz
> A H 11.11.11.2/32 11.11.11.2 254 0 1w2d to-jazz
> C H 11.11.11.255/32 0 0 1w2d to-jazz
> C 12.12.12.0/24 0 0 1w3d to-two
O 12.12.12.0/24 12.12.12.1 110 1 to-two
> C H 12.12.12.0/32 0 0 1w3d to-two
> C H 12.12.12.1/32 0 0 1w3d to-two
> A H 12.12.12.2/32 12.12.12.2 254 0 1w3d to-two
> C H 12.12.12.255/32 0 0 1w3d to-two
> C 13.13.13.0/24 0 0 1w3d to-three
O 13.13.13.0/24 13.13.13.1 110 1 to-three
> C H 13.13.13.0/32 0 0 1w3d to-three
> C H 13.13.13.1/32 0 0 1w3d to-three
> A H 13.13.13.2/32 13.13.13.2 254 0 1w3d to-three
> C H 13.13.13.255/32 0 0 1w3d to-three
> O 15.15.15.0/24 11.11.11.2 110 2 1w2d to-jazz
> O 34.34.34.0/24 13.13.13.2 110 2 1w2d to-three
> O 45.45.45.0/24 11.11.11.2 110 3 1w2d to-jazz
> 13.13.13.2 to-three
[rock1200]rock1200#
1.13 Step 10: Check OSPF Statistics
Run the show ospf statistics [instance-id] [detail] command to verify traffic statistics accumulated for all OSPF processes running on the router.
Run the show ospf statistics interface if-name] command to verify OSPF statistics at the interface level. In the Drop column, check for dropped packets.
Run the show port counters detail command to check the interface counters. For more information about this command, see the General Troubleshooting Guide.
The following example displays output from the show ospf statistics command:
[rock1200]rock1200#show ospf statistics
--- OSPF Statistics for Instance 1 ---
Max flood queue length : 3 Interval : 1w 3d 00:46:35
LSAs received : 8891 LSAs sent : 9335
LSAs changes received : 36 LSA Retransmissions : 3
Packet Retransmissions : 3 RIB initializations : 1
Routes downloaded : 24 Routes deleted : 3
Host Routes Queued : 11 Normal Routes Queued: 16
Priority Routes Queued : 0 Total Routes Queued : 27
Download Errors : 0 RIB IPC messages : 20
Download SPF Delays : 0 SPF Download Delays : 0
DC Indicate originated : 0 DC Indicate purged : 0
DC DoNotAge purged : 0
Hello DD LSR LSU ACK
Sent 259511 11 4 9253 8804
Recv 258837 14 4 8843 9242
[rock1200]rock1200#
[rock1200]rock1200#show ospf statistics interface to-jazz
--- OSPF Statistics for Interface 11.11.11.1/Instance 1 ---
Interface Events : 4 Interval : 3d 22:06:25
LSAs received : 1595 LSAs sent : 1230
Max ACK queue length: 11 Max flood queue size: 6
Hello DD LSR LSU ACK
Sent 33879 3 1 1212 1547
Recv 33879 2 0 1565 1208
[rock1200]rock1200#
1.14 Step 11: Examine the OSPF SPF Log
Run the show ospf spf log command to display the SPF calculation timing calculation log. Verify that SPF ran and investigate network instabilities. The SPF log includes a description of what triggered SPF recalculations—for example, when a new LSA arrives. This command shows which LSAs change most frequently and what triggers the SPF calculations.
- Note:
- If the SPF log is not running as expected, check the following
SPF scheduling configuration parameters:
- fast-convergence
- spf-timers
[rock1200]rock1200#show ospf spf log
--- OSPF SPF Route Calculation Timing Log ---
Maximum SPF-Phase Timings
When (elapsed) Instance/Area Phase Duration
1w 2d 23:53:28 1/3.0.0.4 Intra 1 ms
1w 2d 23:18:44 1/3.0.0.4 Summary < 1 ms
1w 2d 23:19:38 1/N/A External 1 ms
1w 2d 23:18:44 1/2.0.0.0 NSSA < 1 ms
Most Recent SPF-Phase Timings
When (elapsed) Instance/Area Phase Duration
1w 2d 23:18:45 1/2.0.0.0 NSSA < 1 ms
1w 2d 23:18:45 1/N/A External < 1 ms
1w 2d 23:18:45 1/3.0.0.4 Summary < 1 ms
1w 2d 23:18:45 1/0.0.0.0 Summary < 1 ms
1w 2d 23:18:45 1/0.0.0.0 Intra < 1 ms
1w 2d 23:18:45 1/3.0.0.4 Intra < 1 ms
1w 2d 23:18:45 1/2.0.0.0 Intra < 1 ms
1w 2d 23:18:49 1/2.0.0.0 NSSA < 1 ms
1w 2d 23:18:49 1/N/A External < 1 ms
1w 2d 23:18:49 1/3.0.0.4 Summary < 1 ms
1w 2d 23:18:49 1/0.0.0.0 Summary < 1 ms
1w 2d 23:18:49 1/0.0.0.0 Intra < 1 ms
1w 2d 23:18:49 1/3.0.0.4 Intra < 1 ms
1w 2d 23:18:49 1/2.0.0.0 Intra < 1 ms
1w 2d 23:18:54 1/2.0.0.0 NSSA < 1 ms
1w 2d 23:18:54 1/N/A External < 1 ms
1w 2d 23:18:54 1/3.0.0.4 Summary < 1 ms
1w 2d 23:18:54 1/0.0.0.0 Summary < 1 ms
1w 2d 23:18:54 1/0.0.0.0 Intra < 1 ms
1w 2d 23:18:54 1/3.0.0.4 Intra < 1 ms
1w 2d 23:18:54 1/2.0.0.0 Intra < 1 ms
1w 2d 23:18:55 1/2.0.0.0 NSSA < 1 ms
1w 2d 23:18:55 1/N/A External < 1 ms
1w 2d 23:18:55 1/3.0.0.4 Summary < 1 ms
1w 2d 23:18:55 1/0.0.0.0 Summary < 1 ms
1w 2d 23:18:55 1/0.0.0.0 Intra < 1 ms
1w 2d 23:18:55 1/3.0.0.4 Intra < 1 ms
1w 2d 23:18:55 1/2.0.0.0 Intra < 1 ms
1w 2d 23:18:59 1/2.0.0.0 NSSA < 1 ms
1w 2d 23:18:59 1/N/A External < 1 ms
. . .1.15 Step 12: Check OSPF Logs
Use the show log | grep ospf command to filter the log for entries related to OSPF.
- Note:
- You must configure the log-neighbor-up-down command to log an informational message when a neighbor transitions to or from full adjacency state.
1.16 Step 13: Monitor OSPF Events
Run the monitor ospf commands to monitor OSPF events in real time. You can use these commands to troubleshoot intermittent issues.
|
Command |
Description |
|---|---|
|
monitor ospf interface |
Display continuously updated information about OSPF interfaces. |
|
monitor ospf neighbors |
Display continuously updated information about OSPF neighbors. |
|
monitor ospf spf last |
Display continuously updated information about OSPF statistics. |
|
monitor ospf spf statistics |
Display continuously updated information about the most recent OSPF SPF calculation. |
1.16.1 Monitor OSPF Interface
Run the monitor ospf interface command to display continuously updated information about OSPF interfaces.
[rock1200]rock1200#monitor ospf interface --- OSPF Neighbors for Instance 1/Router ID 11.0.0.0 --- NeighborID NeighborAddress Pri State DR-State IntfAddress TimeLeft 0.0.0.4 34.34.34.2 1 Full Other 0.0.0.4 0 22.0.0.0 11.11.11.2 1 Full DR 11.11.11.1 37 0.0.0.2 12.12.12.2 1 Full DR 12.12.12.1 35 0.0.0.3 13.13.13.2 1 Full BDR 13.13.13.1 36 % enter ctrl-C to exit monitor mode, monitor duration(sec): 600 (00:00:02)
1.16.2 Monitor OSPF Neighbors
Run the monitor ospf neighbors command to display continuously updated information about OSPF neighbors.
[rock1200]rock1200#monitor ospf neighbors --- OSPF Neighbors for Instance 1/Router ID 11.0.0.0 --- NeighborID NeighborAddress Pri State DR-State IntfAddress TimeLeft 0.0.0.4 34.34.34.2 1 Full Other 0.0.0.4 0 22.0.0.0 11.11.11.2 1 Full DR 11.11.11.1 36 0.0.0.2 12.12.12.2 1 Full DR 12.12.12.1 34 0.0.0.3 13.13.13.2 1 Full BDR 13.13.13.1 35 % enter ctrl-C to exit monitor mode, monitor duration(sec): 600 (00:00:02)
1.16.3 Monitor OSPF SPF Statistics
Run the monitor ospf spf last to display continuously updated information about the most recent OSPF SPF route calculation.
[rock1200]rock1200#monitor ospf spf last --- Most Recent OSPF SPF Route Calculation --- When (elapsed) Instance/Area Phase Duration 2w 1d 00:28:38 1/2.0.0.0 NSSA < 1 ms 2w 1d 00:28:38 1/N/A External < 1 ms 2w 1d 00:28:38 1/3.0.0.4 Summary < 1 ms 2w 1d 00:28:38 1/0.0.0.0 Summary < 1 ms 2w 1d 00:28:38 1/0.0.0.0 Intra < 1 ms 2w 1d 00:28:38 1/3.0.0.4 Intra < 1 ms 2w 1d 00:28:38 1/2.0.0.0 Intra < 1 ms % enter ctrl-C to exit monitor mode, monitor duration(sec): 600 (00:00:02)
1.16.4 Monitor OSPF Statistics
Run the monitor ospf statistics to display continuously updated information about OSPF traffic statistics.
Make sure the Sent and Received columns are incrementing. In the Drop column, check for drop packets.
[rock1200]rock1200#monitor ospf statistics
--- OSPF Statistics for Instance 1 ---
Max flood queue length : 3 Interval : 1w 3d 01:19:08
LSAs received : 8912 LSAs sent : 9357
LSAs changes received : 36 LSA Retransmissions : 3
Packet Retransmissions : 3 RIB initializations : 1
Routes downloaded : 24 Routes deleted : 3
Host Routes Queued : 11 Normal Routes Queued: 16
Priority Routes Queued : 0 Total Routes Queued : 27
Download Errors : 0 RIB IPC messages : 20
Download SPF Delays : 0 SPF Download Delays : 0
DC Indicate originated : 0 DC Indicate purged : 0
DC DoNotAge purged : 0
Hello DD LSR LSU ACK
Sent 260097 11 4 9274 8825
Recv 259422 14 4 8864 9263
% enter ctrl-C to exit monitor mode, monitor duration(sec): 600 (00:00:04)
1.17 Step 14: Debug OSPF
Run the debug opsf packet errors command to check for MTU, authentication, interface, and area ID issues.
The following table lists error messages that can appear when you run this command, along with the recommended actions to resolve the issues.
|
# |
Error Message |
|---|---|
|
1 |
"OSPF-1 NBR 1.2.3.4: MTU 567 less than our mtu (1500)" Recommended Action: 1. Check MTU configuration by running the show ip interface command on the interfaces that have the mismatched MTUs. 2. Change the router MTU to match the neighbor MTU. |
|
2 |
"OSPF-1: Duplicate DD packet from slave NBR 1.2.3.4 flags: M,M,I options: 2 seq: 3450293" Recommended Action: The slave in a DD exchange has received a packet with a sequence earlier than the one it already has, which means there is a duplicate. Verify that the values are what you expect for the following options. The values need to match the interfaces between two communicating routers.
|
|
3 |
"OSPF-1: Duplicate DD packet from master NBR 1.2.3.4 flags: M,M,I options: 2 seq: 345234098" Recommended Action: The master in a DD exchange has received a packet with a sequence earlier than the one it already has, which means there is a duplicate. Verify that the values are what you expect for the following options. The values need to match the interfaces between two communicating routers.
|
|
4 |
"OSPF-1 NBR 1.2.3.4: invalid LS recv Type 5 (AS-Ext) for this area/interface" Recommended Action: Make sure the area is not a stub or an NSSA area. Type 5 LSAs are not allowed in these areas. |
|
5 |
"OSPF-1 LSU AS-Ext 9.10.11.12 [5.6.7.8] from 1.2.3.4: invalid type" Recommended Action: Make sure the area is not a stub or an NSSA area. Type 5 LSAs are not allowed in these areas. |
|
6 |
"OSPF-1: No current keys in key-chain somePolicyName interface 11.0.0.1 (someIntfName)" Recommended Action: Check the authentication configuration. |
|
7 |
Dec 13 09:37:11: %OSPF-7-PCK_ERRORS: Recv invalid Hello packet 13.1.1.1->224.0.0.5 area 0.0.0.0: No interface Recommended Action: Verify that the interface for which you are receiving the Hello packet has OSPF enabled. |
|
8 |
Nov 22 23:14:55.632: [0001]: %OSPF-7-PCK_ERRORS: OSPF-1: Recv int-to-UELKSRPP01 invalid Database Description packet 10.0.9.14->224.0.0.5 area 0.0.0.0: BFD DOWN Nov 22 23:14:11.331: [0001]: %OSPF-7-PCK_ERRORS: OSPF-1: Recv int-to-UELKSRPP01 invalid Hello packet 10.0.9.14->224.0.0.5 area 0.0.0.0: BFD DOWN Recommended Action: Check if BFD keepalives are being exchanged on OSPF neighbor interfaces. If not flap the ports or check if the BFD configuration is complete. |
| Caution! | ||
Risk of performance loss. Enabling the generation of debug messages can severely affect system performance. To reduce the risk, exercise caution when enabling the generation of debug messages on a production system. We highly recommend that you run this command during a maintenance window. | ||
2 Troubleshooting Specific OSPF Issues
This section describes how to troubleshoot specific OSPF routing problems. For more information about troubleshooting OSPF adjacency, see Troubleshooting General OSPF Issues.
2.1 Troubleshooting OSPF Neighbor States
Use the following sample OSPF topology as a guide to troubleshoot specific OSPF issues that follow in subsequent sections.
Figure 3 Sample OSPF Topology for Troubleshooting Specific Issues
Figure 4 External Routes
2.1.1 Init State
The Init state specifies that the router has received a Hello packet from its neighbor, but the receiving router ID is not included in the Hello packet. When a router receives a Hello packet from a neighbor, it must list the sender's router ID in its Hello packet as an acknowledgment that it received a valid Hello packet.
When the neighbor is stuck in the Init state, a local router likely is not listed in a neighbor's Hello packets because the neighbor has not received Hello packets from the local router. Run the ping and traceroute commands to verify that the links between routers are operational. If a ping between routers is not successful, the link is not functioning properly and you need to troubleshoot it.
Consider the following when troubleshooting the Init state:
- If any access lists are defined on the neighbor interface,
the destination IP of 224.0.0.5 must be permitted
in the access list. OSPF Hello packets have a destination address
of 224.0.0.5 (the all ospf routers multicast
address).
Recommended Action: To verify the access list, run the show access-group command. - There may be a Layer 2 or configuration problem preventing
multicast packets from reaching the neighboring router.
Recommended Action: Type the ping command to the multicast address to see if responses are received from the neighboring routers if a ping to 224.0.0.5 from the rock1200 context on the rock1200 router does not return a response. - Authentication is not enabled on both sides. The router
on which authentication is not enabled still processes Hello packets
from the neighbor and sees the neighbor in the init state.
Recommended Action: To correct this problem, enable authentication on both sides. Make sure they are using the same authentication type. - Hellos are getting lost on one side at Layer 2.
- For virtual links, authentication is enabled on only
one side.
Recommended Action: Enable authentication both sides.
In the following in example, check the state and reachablity of the OSPF neighbor.
[local]SE800_10.192.16.82#show ospf neighbor detail --- OSPF Neighbor 24.24.24.24 Area 0.0.0.0 Instance 100 --- Address : 2.1.1.1 Interface Addr : 2.1.1.2 State : Init DR State : Other Cost : 1 DR Priority : 1 DR Router ID : 0.0.0.0 BDR Router ID : 0.0.0.0 LSA Request : 0 LSA Retrans : 0 DB Exchange : 0 Time Till Dead : 39 Hello Options : E,O DD Options :
[local]SE800_10.192.16.82#ping 2.1.1.1 PING 2.1.1.1 (2.1.1.1): source 2.1.1.2, 36 data bytes, timeout is 1 second !!!!! ----2.1.1.1 PING Statistics---- 5 packets transmitted, 5 packets received, 0.0% packet loss round-trip min/avg/max/stddev = 1.638/2.219/2.928/0.595 ms [local]SE800_10.192.16.82#tra [local]SE800_10.192.16.82#traceroute 2.1.1.1 se_traceroute to 2.1.1.1 (2.1.1.1), 30 hops max, 40 byte packets 1 2.1.1.1 (2.1.1.1) 5.592 ms 3.223 ms 2.796 ms [local]SE800_10.192.16.82#
In the following example, you run the ping size command to determine if the entire MTU can be used. Sometimes both routers have the same configured IP MTU but network equipment between the two routers will not pass the packets of maximum size.
You then run the show ospf interface detail command to display detailed information about the OSPF interface.
[local]SE800_10.192.16.82#ping 2.1.1.1 size 1500 PING 2.1.1.1 (2.1.1.1): source 2.1.1.2, 1500 data bytes, timeout is 1 second !!!!! <--Indicates a successful ping. ----2.1.1.1 PING Statistics---- 5 packets transmitted, 5 packets received, 0.0% packet loss round-trip min/avg/max/stddev = 1.909/2.650/3.817/0.794 ms [local]SE800_10.192.16.82#
[local]SE800_10.192.16.82#show ospf interface detaill
--- OSPF Interface 2.1.1.2 Area 0.0.0.0 Instance 100 ---
Network Type : broadcast Mask : 255.255.255.252
Cost : 1 Logical Intf : 1/3
MTU : 1500 Physical Intf : ethernet 1/3
State : BDR Priority : 1
Hello Interval : 10 Dead Interval : 40
Transmit Delay : 1 Retransmit Int : 5
DR Router ID : 24.24.24.24 DR IP Address : 2.1.1.1
BDR Router ID : 2.1.1.2 BDR IP Address : 2.1.1.2
Ack Queued : 0 Flood Queued : 0
Ack Delay : 2 Authentication : None <--Make sure both sides use the
<--same authentication type.
LSA Count : 0 LSA Checksum : 0
Demand Circuit : No Flood Reduction: No
Neighbor Count : 1
Neighbor List (1 Adjacent):
24.24.24.24
[local]SE800_10.192.16.82#
2.1.2 2-Way State
The 2-way state indicates that the router has seen its own router ID in the Neighbor field of the neighbor's Hello packet. Receiving a Database Description (DD) packet from a neighbor in the init state will also a cause a transition to 2-way state. The OSPF neighbor 2-way state is not a cause for concern.
This state indicates that bidirectional communication has been established between two routers—each router has seen the other's Hello packet, and the router receiving the Hello packet sees its own router ID in the received Hello packet's neighbor field. At this stage, a router can establish adjacency with this neighbor. On broadcast media and nonbroadcast multiaccess networks (NBMA), a router reaches full state only with the designated router (DR) and the backup designated router (BDR); it stays in the 2-way state with all other neighbors. On point-to-point and point-to-multipoint networks, a router reaches full state with all connected routers.
At the end of this stage, the DR and BDR for broadcast and nonbroadcast multiaccess networks are elected.
If the router interfaces are not in a waiting state, the router performs DR and BDR election. Once DR and BDR are elected, a router attempts to form a full adjacency with a neighbor if one of the two routers is the DR or BDR. OSPF routers become fully adjacent to routers with which they have successfully completed the database synchronization process. This is how OSPF routers within an area exchange link-state information to populate their databases with the same information. This database synchronization process occurs only if one of the two routers is a DR or BDR in the case of broadcast multiaccess networks. This database synchronization process is only executed between two routers if one of the two routers is the DR or BDR.
- Note:
- If the OSPF neighbor is stuck in 2-way state, router-priority 0 might be configured on all routers.
The following example displays the state of OSPF interfaces.
[local]SE800_10.192.16.82#show ospf interface detail --- OSPF Interface 2.1.1.2 Area 0.0.0.0 Instance 100 --- Network Type : broadcast Mask : 255.255.255.252 Cost : 1 Logical Intf : 1/3 MTU : 1500 Physical Intf : ethernet 1/3 State : BDR Priority : 1 Hello Interval : 10 Dead Interval : use Transmit Delay : 1 Retransmit Int : 5 DR Router ID : 24.24.24.24 DR IP Address : 2.1.1.1 BDR Router ID : 2.1.1.2 BDR IP Address : 2.1.1.2 Ack Queued : 0 Flood Queued : 0 Ack Delay : 2 Authentication : None LSA Count : 0 LSA Checksum : 0 Demand Circuit : No Flood Reduction: No Neighbor Count : 1 Neighbor List (1 Adjacent): 24.24.24.24 [local]SE800_10.192.16.82# --- OSPF Neighbor 24.24.24.24 Area 0.0.0.0 Instance 100 --- Address : 2.1.1.1 Interface Addr : 2.1.1.2 State : 2-Way DR State : Other Cost : 1 DR Priority : 1 DR Router ID : 0.0.0.0 BDR Router ID : 0.0.0.0 LSA Request : 0 LSA Retrans : 0 DB Exchange : 0 Time Till Dead : 38 Hello Options : E,O DD Options : [local]SE800_10.192.16.82#sh ospf neig detail --- OSPF Neighbor 24.24.24.24 Area 0.0.0.0 Instance 100 --- Address : 2.1.1.1 Interface Addr : 2.1.1.2 State : 2-Way DR State : Other Cost : 1 DR Priority : 1 DR Router ID : 0.0.0.0 BDR Router ID : 0.0.0.0 LSA Request : 0 LSA Retrans : 0 DB Exchange : 0 Time Till Dead : 36 Hello Options : E,O DD Options : [local]SE800_10.192.16.82#
2.1.3 OSPF Neighbor Stuck in Exstart or Exchange State
A router gets stuck in ExStart or Exchange state more frequently when interoperating with another vendor's router.
Once the DR and BDR are elected, link-state information exchange can start between the routers and their DR and BDR. In the ExStart state, the routers and their DR and BDR establish a master-slave relationship and choose the initial sequence number to establish an adjacency. The router with the higher router ID becomes the master and starts the exchange, and is the only router that can increment the sequence number.
- Note:
- Make sure that the router ID is unique within the entire internetwork; otherwise, OSPF neigborship will "not" form.
In the Exchange state, OSPF routers exchange DD packets. DD contain link-state advertisement (LSA) headers only and describe the contents of the entire link-state database. Each DD packet has a sequence number that can be incremented only by a master that is explicitly acknowledged by the slave. Routers also send link-state request packets and link-state update packets (which contain the entire LSA) in this state. The contents of the DD packets received are compared to the information contained in the routers link-state database to check if new or more current link-state information is available with the neighbor.
OSPF neighbors in Exstart or exchange state are trying to exchange DD packets. The adjacency should continue past this state. If it does not, there is a problem with the DD exchange, such as a maximum transmission unit (MTU) mismatch or receipt of an unexpected DD sequence number.
- Note:
- Make sure that the router ID is unique within the entire internetwork; otherwise, no neighborship will form.
An OSPF neighbor can be stuck in ExStart or Exchange state for the following reasons:
- Duplicate router IDs on neighbors. This problem usually manifests before database exchange.
- Unable to ping without using specific maximum transmission unit (MTU) size.
- Broken unicast connectivity because of the following:
- Wrong VC or DLCI mapping in the Frame Relay or ATM switch
- An access list blocking the unicast
- Incorrect NAT translation of the unicast packet
- Mismatched interface MTU
The problem occurs when the MTU settings for neighboring router interfaces do not match. If the router with the higher MTU sends a packet larger than the MTU set on the neighboring router, the neighboring router ignores the packet. When this occurs, the output of the show ospf neighbor detail command displays output similar to what is shown below.
[local]SE800_10.192.16.82#show ospf neighbor detail --- OSPF Neighbor 24.24.24.24 Area 0.0.0.0 Instance 100 --- Address : 2.1.1.1 Interface Addr : 2.1.1.2 State : ExStart DR State : DR Cost : 1 DR Priority : 1 DR Router ID : 2.1.1.1 BDR Router ID : 2.1.1.2 LSA Request : 0 LSA Retrans : 0 DB Exchange : 0 Time Till Dead : 36 Hello Options : E,O DD Options : E,O [local]SE800_10.192.16.82#show ospf neighbor detail --- OSPF Neighbor 24.24.24.24 Area 0.0.0.0 Instance 100 --- Address : 2.1.1.1 Interface Addr : 2.1.1.2 State : Exchange DR State : DR Cost : 1 DR Priority : 1 DR Router ID : 2.1.1.1 BDR Router ID : 2.1.1.2 LSA Request : 0 LSA Retrans : 0 DB Exchange : 3 Time Till Dead : 31 Hello Options : E,O DD Options : E,O [local]SE800_10.192.16.82#show ospf neighbor detail --- OSPF Neighbor 24.24.24.24 Area 0.0.0.0 Instance 100 --- Address : 2.1.1.1 Interface Addr : 2.1.1.2 State : Exchange DR State : DR Cost : 1 DR Priority : 1 DR Router ID : 2.1.1.1 BDR Router ID : 2.1.1.2 LSA Request : 0 LSA Retrans : 0 DB Exchange : 3 Time Till Dead : 38 Hello Options : E,O DD Options : E,O local]SE800_10.192.16.82#show ospf neighbor detail --- OSPF Neighbor 24.24.24.24 Area 0.0.0.0 Instance 100 --- Address : 2.1.1.1 Interface Addr : 2.1.1.2 State : Exchange DR State : DR Cost : 1 DR Priority : 1 DR Router ID : 2.1.1.1 BDR Router ID : 2.1.1.2 LSA Request : 0 LSA Retrans : 0 DB Exchange : 3 Time Till Dead : 33 Hello Options : E,O DD Options : E,O [local]SE800_10.192.16.82#
After you have determined that OSPF is stuck in the Exchange or ExStart state, run the debug ospf packet errors command to determine the cause of the fault.
In the following example, the debug ospf packet errors output indicates mismatched MTUs.
Recommended Action:
- Run the show ip interface command on the interfaces that have the mismatched MTUs.
- Change either router MTU to match the neighbor MTU.
| Caution! | ||
|
Risk of performance loss. Enabling the generation of debug messages
can severely affect system performance. To reduce the risk, exercise
caution when enabling the generation of debug messages on a production
system. We highly recommend that you issue this command during a maintenance
window.
| ||
[local]SE800_10.192.16.82#debug ospf packet errors [local]SE800_10.192.16.82#Dec 1 17:24:57: [0001]: %OSPF-7-PCK_ERRORS: OSPF-100 NBR 2.1.1.1: MTU 1400 less than our mtu (1500) Dec 1 17:25:02: [0001]: %OSPF-7-PCK_ERRORS: OSPF-100 NBR 2.1.1.1: MTU 1400 less than our mtu (1500) Dec 1 17:25:26: [0001]: %OSPF-7-PCK_ERRORS: OSPF-100 NBR 2.1.1.1: MTU 1400 less than our mtu (1500) Dec 1 17:25:31: [0001]: %OSPF-7-PCK_ERRORS: OSPF-100 NBR 2.1.1.1: MTU 1400 less than our mtu (1500) Dec 1 17:25:36: [0001]: %OSPF-7-PCK_ERRORS: OSPF-100 NBR 2.1.1.1: MTU 1400 less than our mtu (1500) Dec 1 17:25:41: [0001]: %OSPF-7-PCK_ERRORS: OSPF-100 NBR 2.1.1.1: MTU 1400 less than our mtu (1500) Dec 1 17:25:46: [0001]: %OSPF-7-PCK_ERRORS: OSPF-100 NBR 2.1.1.1: MTU 1400 less than our mtu (1500) Dec 1 17:25:51: [0001]: %OSPF-7-PCK_ERRORS: OSPF-100 NBR 2.1.1.1: MTU 1400 less than our mtu (1500) Dec 1 17:25:56: [0001]: %OSPF-7-PCK_ERRORS: OSPF-100 NBR 2.1.1.1: MTU 1400 less than our mtu (1500) Dec 1 17:26:01: [0001]: %OSPF-7-PCK_ERRORS: OSPF-100 NBR 2.1.1.1: MTU 1400 less than our mtu (1500) Dec 1 17:26:06: [0001]: %OSPF-7-PCK_ERRORS: OSPF-100 NBR 2.1.1.1: MTU 1400 less than our mtu (1500) Dec 1 17:26:11: [0001]: %OSPF-7-PCK_ERRORS: OSPF-100 NBR 2.1.1.1: MTU 1400 less than our mtu (1500) Dec 1 17:26:36: [0001]: %OSPF-7-PCK_ERRORS: OSPF-100 NBR 2.1.1.1: MTU 1400 less than our mtu (1500 )
[local]SE800_10.192.16.82#show ip interface 1/3 Intf name: 1/3 Intf state: Up MTU: 1500 IP address: 2.1.1.2 Prefix len: 30 OSPF instance: 100 OSPF net type: broadcast OSPF cost: 1 OSPF state: BDR Resoln type: Arp ARP timeout: 3600 ARP proxy: Disabled ARP secured: Disabled Number of Bound Circuits (incl. dynamic) = 1 Bindings: (Total Bound Circuits 1) Encapsulation Circuit ethernet 1/3 [local]SE800_10.192.16.82# [local]SE1200_10.192.17.224#show ip interface 2/1 Intf name: 2/1 Intf state: Up MTU: 1400 IP address: 2.1.1.1 Prefix len: 30 OSPF instance: 100 OSPF net type: broadcast OSPF cost: 1 OSPF state: DR Resoln type: Arp ARP timeout: 3600 ARP proxy: Disabled ARP secured: Disabled Number of Bound Circuits (incl. dynamic) = 1 Bindings: (Total Bound Circuits 1) Encapsulation Circuit ethernet 2/1 [local]SE1200_10.192.17.224# [local]SE1200_10.192.17.224(config)#context local [local]SE1200_10.192.17.224(config-ctx)#interface 2/1 [local]SE1200_10.192.17.224(config-if)#ip mtu 1500 [local]SE1200_10.192.17.224(config-if)#commit Transaction committed. [local]SE1200_10.192.17.224(config-if)#end [local]SE1200_10.192.17.224#
2.1.4 Loading State
In the loading state, routers send link-state request packets. During the database exchange, if a router receives an outdated or missing LSA, it requests that LSA by sending a link-state request packet. Neighbors that do not transition beyond this state are most likely exchanging corrupted LSAs.
The most common causes of this problem include:
- Mismatched MTU
Recommended Action:
1. Run the show ip interface command on the interfaces that have the mismatched MTUs.
2. Change either router MTU to match the neighbor MTU. - Corrupted link-state request packet
Recommended Action: Run the clear ospf neighbor all command to force adjacency reestablishment
2.1.5 Full State
In a Full state, routers are fully adjacent with each other. All the LSAs within the area are exchanged, and the router databases are fully synchronized. Full is the normal state for an OSPF router. Being stuck in another state indicates that the router cannot form adjacencies. The 2-way state is normal on broadcast and NBMA networks. In these networks, routers achieve the full state with their DR and BDR only. Other neighbors always see each other as 2-way.
[local]SE800_10.192.16.82#show ospf neighbor detail --- OSPF Neighbor 24.24.24.24 Area 0.0.0.0 Instance 100 --- Address : 2.1.1.1 Interface Addr : 2.1.1.2 State : Full DR State : DR Cost : 1 DR Priority : 1 DR Router ID : 2.1.1.1 BDR Router ID : 2.1.1.2 LSA Request : 0 LSA Retrans : 0 DB Exchange : 0 Time Till Dead : 32 Hello Options : E,O DD Options : E,O [local]SE800_10.192.16.82
2.1.6 show ospf neighbor Output Is Empty
When the show ospf neighbor detail command displays no output, run the show ip interface and show ip interface detail commands to verify the state of the interfaces.
Table 9 lists the common causes for this problem:
|
# |
Possible Reason |
Checked? |
|---|---|---|
|
1 |
OSPF is not enabled on the interface. Layer 1 or 2 is down. |
|
|
2 |
The interface is defined as passive under OSPF. |
|
|
3 |
A subnet number or mask has been mismatched over a broadcast links. |
|
|
4 |
The Hello or dead interval has been mismatched. |
|
|
5 |
The authentication type (plain text versus MD5) has been mismatched. |
|
|
6 |
An area ID has been mismatched. |
|
|
7 |
Stub, transit, or NSSA area options have been mismatched. |
|
|
8 |
An OSPF adjacency exists over an asynchronous interface. |
|
|
9 |
No network type or neighbor is defined over NBMA (Frame Relay). |
Run the show ip interface command to verify that the interface state is Up. Run the show ospf interface command to display detailed information about a specific OSPF interface.
[local]SE800_10.192.16.82#show ip interface 1/3 Intf name: 1/3 Intf state: Up MTU: 1500 IP address: 2.1.1.2 Prefix len: 30 OSPF instance: 100 OSPF net type: broadcast OSPF cost: 1 OSPF state: BDR Resoln type: Arp ARP timeout: 3600 ARP proxy: Disabled ARP secured: Disabled Number of Bound Circuits (incl. dynamic) = 1 Bindings: (Total Bound Circuits 1) Encapsulation Circuit ethernet 1/3 [local]SE800_10.192.[local]SE800_10.192.16.82#show ospf interface 2.1.1.2 detail --- OSPF Interface 2.1.1.2 Area 0.0.0.0 Instance 100 --- Network Type : broadcast Mask : 255.255.255.252 Cost : 1 Logical Intf : 1/3 MTU : 1500 Physical Intf : ethernet 1/3 State : BDR Priority : 1 Hello Interval : 10 Dead Interval : 40 Transmit Delay : 1 Retransmit Int : 5 DR Router ID : 24.24.24.24 DR IP Address : 2.1.1.1 BDR Router ID : 2.1.1.2 BDR IP Address : 2.1.1.2 Ack Queued : 0 Flood Queued : 0 Ack Delay : 2 Authentication : None LSA Count : 0 LSA Checksum : 0 Demand Circuit : No Flood Reduction: No Neighbor Count : 1 Neighbor List (1 Adjacent): 24.24.24.24 [local]SE800_10.192.16.82# 16.82#
2.2 Troubleshooting OSPF Routing Tables
Most OSPF problems are caused by reachability problems. When no adjacency issues exist, check for route update problems. Route update problems are difficult to isolate because the routing table can be populated with routing information from multiple sources.
Figure 5 OSPF Routing Table Flowchart
The common causes of routing update problems for OSPF include missing OSPF routes and missing external routes.
If a route is not being learned in the rest of the area or domain, verify that the route in the OSPF process has been correctly configured.
2.2.1 Missing OSPF Routes
If all OSPF routes are missing, the OSPF neighbor likely is not in a Full state.
Do the following:
- Check the physical link.
- Ping the neighbor IP interface.
- If you can ping the neighbor IP address, use the information in Troubleshoot OSPF Neighbor States to verify the state of neighbor adjacency.
Non-OSPF routes redistributed into OSPF are called external routes. In the following example, the SmartEdge SE100 and the SmartEdge SE800 routers are running IS-IS. The SE800 router redistributes its IS-IS routes into OSPF and, as a result, the SE1200 router can learn the route to reach the SE100 router through OSPF.
Figure 6 External Routes
When the external routes are missing, do the following:
- Check if the External LSA Exists in the OSPF Database
- Check if the IS-IS Routes
from Originating Router
Make sure that originating router is not trying to redistribute into a stub area.
- Check the Forwarding Address
2.2.1.1 Step 1: Check if the External LSA Exists in the OSPF Database
[local]SE800_10.192.16.82#show ospf database external detail
--- OSPF Link State Database for Instance 100/Router ID 172.16.8.6 ---
--- External LSA 172.16.57.5 ---
Link State Id : 172.16.57.5 Advertising Router : 172.16.8.6
Sequence Number : 0x80000006 Checksum : 0xba96
Options : E,DC Length : 36
Mask : 255.255.255.255 Metric : 660
Forwarding Addr : 0.0.0.0 Type : 2
Tag : 0x0 Age : 1522
<-- 0.0.0.0 defaults to the originating router address (the advertising router).2.2.1.2 Step 2: Check IS-IS routes from the Originating Router.
[local]se100_16_112#show isis database l2 detail IS-IS level 2 link-state database for tag PBN1: LSPID Sequence Checksum Holdtime AT/OL Len SE800_10.192.1.00-00 0x323 0xa659 569 0/0 113 Area Address: 49.0840 NLPID: IP Hostname: SE800_10.192.16.82 Router ID: 172.16.8.6 IP Address: 172.16.8.6 M-Topology: Metric: 650 IS-Extended SE800_10.192.1.01 Metric: 10 IP 172.16.8.6/32 Metric: 650 IP 192.168.210.24/30 SE800_10.192.1.01-00 0x1d9 0x6fff 569 0/0 53 Metric: 0 IS-Extended SE800_10.192.1.00 Metric: 0 IS-Extended se100_16_112.00 se100_16_112.00-00* 0x188 0x8da 1178 0/0 107 Area Address: 49.0840 NLPID: IP Hostname: se100_16_112 Router ID: 172.16.57.5 IP Address: 172.16.57.5 M-Topology: Metric: 650 IS-Extended SE800_10.192.1.01 Metric: 10 IP 172.16.57.5/32 Metric: 650 IP 192.168.210.24/30 Total IS-IS LSP(s) for tag PBN1 in Level-2: 3 [local]se100_16_112#
2.2.1.3 Step 3: Check the Forwarding Address
The forwarding address for external route must be known as an internal OSPF route, and it must be an interarea or intra-area route.
- If the AS-External LSA exists, run the show ospf database external detail command to check the forwarding address.
- If the forwarding address field is 0.0.0.0, run the show ospf border-routers asbr to determine whether the route to the advertising router exists.
- If the forwarding address field is a.b.c.d, run the show ospf route a.b.c.d to determine whether a route to the specified forwarding address exists.
- If a route does not exist, check the network state, and check the entire database.
2.2.2 Missing External Routes
Each OSPF network that is divided into different areas must follow these rules:
- A backbone area (area 0) that combines a set of independent areas into a single domain must exist.
- Each nonbackbone area must be directly connected to the backbone area; this connection can be a simple logical connection through a virtual link.
- If you have an issue, verify that the backbone area has not been partitioned. Given a failure condition, such as link or router down events, carefully check area 0 and verify that it is contiguous.
The most common causes of OSPF not installing external routes in the routing table include:
- The forwarding address is not known through the intra-area or inter-area route.
- The ABR is not generating Type 4 summary LSAs.
The following OSPF problems can happen during redistribution:
- ASBR does not advertise redistributed routes.
- OSPF does not install external routes in the routing table.
To troubleshoot missing summary routes:
- Verify the OSPF Areas.
- Identify and Check the ABR router.
- Verify if the Inter-area Routes are Learned.
- Verify if the Summary LSAs are Learned.
2.2.2.1 Step 1: Verify the Number of OSPF Areas
[local]SE800_10.192.16.82#show ospf area brief --- OSPF Areas for Instance 100/Router ID 172.16.8.6 --- Area Type Intf-Count LSA-Count LSA cksum 0.0.0.0 Regular 2 5 0x00018e9d 0.0.0.1 Regular 1 5 0x0001f305 [local]SE800_10.192.16.82#
2.2.2.2 Step 2: Identify and Check the ABR Router
[[local]SE800_10.192.16.82#show ospf border-routers detail
--- Border Routers for OSPF Instance 100/Router ID 172.16.8.6 ---
Destination : 2.1.1.1 Type : Intra
Dest-type : ABR Cost : 1
Area : 0.0.0.0 Back Link Data : 2.1.1.1
LSDB Type : Router LSDB ID : 2.1.1.1
LSDB Adv Router: 2.1.1.1 Next Hop Count : 1
SPF Version : 8
Next Hop 1 Intf: Next Hop 1 Addr: 2.1.1.1
[local]SE800_10.192.16.82#
[local]SE800_10.192.16.82#show ospf interface
--- OSPF Interfaces for Instance 100/Router ID 172.16.8.6 ---
Addr Len NetworkType Cost Priority State Area
2.1.1.2 30 broadcast 1 1 BDR 0.0.0.0
172.16.8.6 32 loopback 1 1 Loopback 0.0.0.0
12.1.1.1 24 broadcast 1 1 DR 0.0.0.1
[local]SE800_10.192.16.82#
[local]SE800_10.192.16.82#show ospf route
--- OSPF Routes for Instance 100/Router ID 172.16.8.6 ---
Destination Type Dest-Type/Proto Cost Nhops Nhop
2.1.1.0/30 Intra Net 1 1 1/3
12.1.1.0/24 Intra Net 1 1 1/2
22.1.1.0/24 Inter Sum-Net 2 1 2.1.1.1
24.24.24.24/32 Intra Net 2 1 2.1.1.1
172.16.8.6/32 Intra Net 1 1 lo1
2.2.2.3 Step 3: Verify that the Router Has Learned the Inter-area Routes
[local]SE800_10.192.16.82#show ospf route inter-area detail
--- OSPF Routes for Instance 100/Router ID 172.16.8.6 ---
Destination : 22.1.1.0/24 Type : Inter
Dest-type : Sum-Net Cost : 2
Version : 7 SPF Version : 8
Area : 0.0.0.0 Distance : 110
Next Hop Count : 1
Next Hop 1 Intf: Next Hop 1 Addr: 2.1.1.1
[local]SE800_10.192.16.82#
[local]SE800_10.192.16.82#show ip route ospf
Codes: C - connected, S - static, S dv - dvsr, R - RIP, e B - EBGP, i B - IBGP
A,H - derived hidden
O - OSPF, O3 - OSPFv3, IA - OSPF(v3) inter-area,
N1 - OSPF(v3) NSSA external type 1, N2 - OSPF(v3) NSSA external type 2
E1 - OSPF(v3) external type 1, E2 - OSPF(v3) external type 2
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, N - NAT
IPH - IP Host, SUB A - Subscriber address, SUB S - Subscriber static
MIP F - Mobile-IP Foreign Agent, MIP H - Mobile-IP Home Agent
A - Derived Default, MH - Media Nexthop
> - Active Route, * - LSP
Type Network Next Hop Dist Metric UpTime Interface
O 2.1.1.0/30 2.1.1.2 110 1 1/3
O 12.1.1.0/24 12.1.1.1 110 1 1/2
> O IA 22.1.1.0/24 2.1.1.1 110 2 01:43:56 1/3
> O 24.24.24.24/32 2.1.1.1 110 2 02:14:14 1/3
O 172.16.8.6/32 172.16.8.6 110 1 lo1
[local]SE800_10.192.16.82#show ospf route
--- OSPF Routes for Instance 100/Router ID 172.16.8.6 ---
Destination Type Dest-Type/Proto Cost Nhops Nhop
2.1.1.0/30 Intra Net 1 1 1/3
12.1.1.0/24 Intra Net 1 1 1/2
22.1.1.0/24 Inter Sum-Net 2 1 2.1.1.1
24.24.24.24/32 Intra Net 2 1 2.1.1.1
172.16.8.6/32 Intra Net 1 1 lo1
[local]SE800_10.192.16.82#
2.2.2.4 Step 4: Verify that the Router Has Learned the Summary LSAs
[local]SE800_10.192.16.82#show ospf database summary-network all
--- OSPF Link State Database for Instance 100/Router ID 172.16.8.6 ---
Summary Network Link State Advertisements (Area 0.0.0.0)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
12.1.1.0 172.16.8.6 80000004 ea75 E,DC 28 803
22.1.1.0 2.1.1.1 80000004 30eb E,DC 28 1057
Summary Network Link State Advertisements (Area 0.0.0.1)
LinkID AdvertisingRtr Sequence # ChkSm Option Length LSAge
2.1.1.0 172.16.8.6 80000005 5913 E,DC 28 778
22.1.1.0 172.16.8.6 80000004 72e2 E,DC 28 888
24.24.24.24 172.16.8.6 80000005 52b9 E,DC 28 688
172.16.8.6 172.16.8.6 80000005 8220 E,DC 28 638
2.3 Troubleshooting OSPF Route Summarization Problems
OSPF can use two types of summarization:
- Interarea summarization that can be done on the ABR
- External summarization that can be done on the ASBR
Common problems related to summarization in OSPF include:
- A router does not summarize interarea routes.
Cause: The area range command is not configured on the ABR.
- A router does not summarize external routes.
Cause: The summary-address (OSPF) command is not configured on the ASBR.
2.4 Troubleshooting OSPF Not Advertising Routes
The most common reasons for OSPF to not share the database information about a specific link are:
- The neighbors's interface is configured to be passive, and so is not advertising routes.
- The OSPF neighbor (ABR) is not advertising the summary route.
- The OSPF neighbor is not advertising the default route.
- The OSPF neighbor is not advertising external routes.
2.5 Troubleshooting SPF Calculation and Route Flapping
The most common causes of SPF running constantly in the network include:
- An interface flap within the network.
- A neighbor flap within the network.
- A duplicate router ID.
2.6 OSPF Neighbor Not Advertising Default Routes
The most common causes for an OSPF router to not advertise the default route include:
- The originate-default command is missing.
- The default route is missing from the neighbor’s routing table.
- A neighbor is trying to originate a default into a stub area.
- The default-route command at the router OSPF area level is not enabled.