Monitoring Troubleshooting an OSPF Network | OSPF Network Design Solutions

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The following list offers descriptions of fields for the debug ip ospf packet command.

• v:. Indicates the OSPF version.

• t:. Indicates the OSPF packet type. Possible packet types include the following:

• 1. Hello

• 2. Data description

• 3. Link-state request

• 4. Link-state update

• 5. Link-state acknowledgment

• l:. Indicates the OSPF packet length in bytes.

• rid:. Indicates the OSPF router ID.

• aid:. Indicates the OSPF area ID.

• chk:. Indicates the OSPF checksum.

• aut:. Indicates the OSPF authentication type. Possible authentication types are as follows:

• 0. No authentication

• 1. Simple password

• 2. MD5

• auk:. Indicates the OSPF authentication key.

• keyid:. Indicates the MD5 key ID.

• seq:. Indicates the sequence number.

debug ip ospf spf Command

The debug ip ospf spf command enables you to view the actions and events being generated by OSPF’s Shortest Path First (SPF) algorithm. The no form of this command disables debugging output. The basic syntax for this command is as follows:

    [no] debug ip ospf spf

OSPF’s full SPF contains three parts. First, the Dijkstra algorithm calculates the shortest path tree for the area to figure out all the intra-area routes. Then, all summary LSAs are scanned to calculate the inter-area routes. Finally, all external LSAs are scanned to calculate the external routes. If only debug ip ospf spf is done, all information on all three of these steps is shown. This information shows how OSPF decides to add a route from the LSAs and how its cost is calculated. Using the additional keywords displays only the step in which you are interested. Furthermore, for partial SPF, only summary or external LSAs are affected, in which case you would like to do either debug ip ospf spf inter or debug ip ospf spf external to monitor the partial SPF. You can specify an access to filter only calculation for LSA with specific LSA ID.

    OSPF_Router# debug ip ospf spf ?      external       OSPF spf external-route      inter          OSPF spf inter-route      intra          OSPF spf inter-route

This command provides a variety of useful information regarding SPF and the different options.

    OSPF_Router# debug ip ospf spf external    OSPF spf external events debugging is on    OSPF_Router# debug ip ospf spf inter    OSPF spf inter events debugging is on    OSPF_Router# debug ip ospf spf intra    OSPF spf intra events debugging is on

debug ip routing Command

Use the debug ip routing EXEC command to display information about how the routing table is updated. All routing protocol can update the routing table so it is not OSPF-specific. The no form of this command disables debugging output. The basic syntax for this command is as follows:

    [no] debug ip routing

The following example shows sample output generated by the debug ip routing command.

    OSPF_Router# debug ip routing    RT: del 156.226.31.1156/30 via 156.20.18.26, ospf metric [110/4086]    RT: add 156.226.31.1156/30 via 156.20.18.22, ospf metric [110/2108]    RT: add 156.226.31.1156/30 via 156.20.18.26, ospf metric [110/2108]    RT: add 156.226.31.160/30 via 156.20.18.26, ospf metric [110/4086]    RT: del 156.226.31.160/30 via 156.20.18.26, ospf metric [110/4086]    RT: add 156.226.31.160/30 via 156.20.18.22, ospf metric [110/2108]    RT: add 156.226.31.160/30 via 156.20.18.26, ospf metric [110/2108]    RT: add 156.226.31.164/30 via 156.20.18.26, ospf metric [110/4086]    RT: del 156.226.31.164/30 via 156.20.18.26, ospf metric [110/4086]    RT: add 156.226.31.164/30 via 156.20.18.22, ospf metric [110/2108]    RT: add 156.226.31.164/30 via 156.20.18.26, ospf metric [110/2108]    RT: add 156.226.31.188/30 via 156.20.18.22, ospf metric [110/2108]    RT: add 156.226.31.188/30 via 156.20.18.26, ospf metric [110/2108]    RT: add 156.226.31.190/32 via 156.20.18.22, ospf metric [110/2108]    RT: add 156.226.31.190/32 via 156.20.18.26, ospf metric [110/2108]    RT: add 156.226.53.0/24 via 156.20.18.26, ospf metric [110/4086]    RT: add 156.226.54.0/24 via 156.20.18.26, ospf metric [110/4086]    RT: add 156.240.0.0/12 via 156.20.18.22, ospf metric [110/136]    RT: add 156.240.0.0/12 via 156.20.18.26, ospf metric [110/136]    RT: add 159.24.43.0/24 via 156.20.18.22, ospf metric [110/72]    RT: add 159.24.43.0/24 via 156.20.18.26, ospf metric [110/72]    RT: add 192.168.246.37/32 via 156.20.18.26, ospf metric [110/2108]    RT: add 192.168.246.38/32 via 156.20.18.22, ospf metric [110/2108]    RT: add 192.168.246.38/32 via 156.20.18.26, ospf metric [110/2108]    RT: add 192.168.246.39/32 via 156.20.18.22, ospf metric [110/2108]    RT: add 192.168.246.39/32 via 156.20.18.26, ospf metric [110/2108]    RT: add 192.168.246.40/32 via 156.20.18.22, ospf metric [110/2108]    RT: add 192.168.246.40/32 via 156.20.18.26, ospf metric [110/2108]    RT: add 192.168.246.41/32 via 156.20.18.22, ospf metric [110/2108]    RT: add 192.168.246.41/32 via 156.20.18.26, ospf metric [110/2108]    RT: add 192.168.246.42/32 via 156.20.18.22, ospf metric [110/2108]    RT: add 192.168.246.42/32 via 156.20.18.26, ospf metric [110/2108]    RT: add 192.168.246.46/32 via 156.20.18.22, ospf metric [110/2108]    RT: add 192.168.246.46/32 via 156.20.18.26, ospf metric [110/2108]    RT: add 192.168.246.48/32 via 156.20.18.22, ospf metric [110/2108]    RT: add 192.168.246.48/32 via 156.20.18.26, ospf metric [110/2108]    RT: add 192.168.247.0/24 via 156.20.18.26, ospf metric [110/4086]    RT: del 192.168.247.0/24 via 156.20.18.26, ospf metric [110/4086]    RT: add 192.168.247.0/24 via 156.20.18.22, ospf metric [110/2108]    RT: add 192.168.247.0/24 via 156.20.18.26, ospf metric [110/2108]    RT: network 192.168.247.0 is now variably masked    RT: add 192.168.247.2/32 via 156.20.18.22, ospf metric [110/2108]    RT: add 192.168.247.2/32 via 156.20.18.26, ospf metric [110/2108]    RT: add 192.168.247.3/32 via 156.20.18.22, ospf metric [110/2108]    RT: add 192.168.247.3/32 via 156.20.18.26, ospf metric [110/2108]    RT: add 192.168.247.4/32 via 156.20.18.22, ospf metric [110/2108]

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