Designing Implementing an OSPF Network | OSPF Network Design Solutions

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Example: The following command syntax will provide you with a wealth of relevant information regarding the OSPF processes that are currently running on your Cisco router. The entries in this output are defined in Table 8-1 that follows.

    OSPF_ROUTER> show ip ospf     Routing Process ’’ospf 5774’’ with ID 156.20.16.6     Supports only single TOS (TOS0) routes     It is an area border and autonomous system boundary router     Summary Link update interval is 00:30:00 and the update due in 00:00:54     External Link update interval is 00:30:00 and the update due in     00:02:43     Redistributing External Routes from,        connected with metric mapped to 100, includes subnets in        redistribution        bgp 5754 with metric mapped to 50, includes subnets in        redistribution     SPF schedule delay 5 secs, Hold time between two SPFs 10 secs     Number of areas in this router is 2. 2 normal 0 stub        Area BACKBONE(0)           Number of interfaces in this area is 3           Area has no authentication           SPF algorithm executed 9778 times            Area ranges are              156.20.16.0/24 Active(1)        Link State Update Interval is 00:30:00 and due in 00:02:43        Link State Age Interval is 00:20:00 and due in 00:02:43     Area 14        Number of interfaces in this area is 2        Area has no authentication        SPF algorithm executed 30 times        Area ranges are        Link State Update Interval is 00:30:00 and due in 00:00:50        Link State Age Interval is 00:20:00 and due in 00:00:43

Table 8-1 describes some fields that are useful in a troubleshooting environment.

**Table 8-1** `show ip ospf` output definitions
Field	Description

Routing Process “ospf 5774” with ID 56.0.16.6	OSPF Process ID and OSPF router ID
Type of Service	Number of Types of Service supported (Type 0 only)
Type of OSPF Router	Possible types are internal, area border, or autonomous system boundary
Summary Link update interval	Specify summary update interval in hours:minutes:seconds, and time to next update
External Link update interval	Specify external update interval in hours:minutes:seconds, and time to next update
Redistributing External Routes	Lists of redistributed from routes, by protocol
Number of areas	Number of areas in the router, area addresses, and so on
SPF Algorithm	This is run only for route link-state advertisements (LSAs), not for summary LSAs. This command shows the number of times the full SPF algorithm has been run.
Link State Update Interval	Specify router and network link-state update interval in hours:minutes:seconds, and time to next update
Link State Age Interval	Specify max-aged update deletion interval and time until next database cleanup in hours:minutes:seconds

show ip ospf interface Command

You can gain an extensive amount of useful information from the show ip ospf interface command. In this use of the command, a specific interface was selected, but if used as shown here, then it will provide you with information on all interfaces. To display OSPF-related interface information, use the show ip ospf interface EXEC command. The syntax for this command is as follows:

    show ip ospf interface [type number]

Syntax Description:

type: This optional argument represents the interface type.

number: This optional argument represents the interface number.

Usage Guidelines: You can verify that interfaces have been configured in the intended areas. In the example that follows, the serial interface has been placed in area 0.

The show ip ospf interface command also gives the timer intervals including the hello interval. These values must match if the OSPF routers are to become neighbors.

Example: The following is sample output from the show ip ospf interface command when Serial2/0.1 is specified.

    OSPF_ROUTER# show ip ospf interface s2/0.1    Serial2/0.1 is up, line protocol is up      Internet Address 156.20.16.65/27, Area 0      Process ID 5774, Router ID 156.20.16.1, Network Type BROADCAST, Cost:       64      Transmit Delay is 1 sec, State DROTHER, Priority 10      Designated Router (ID) 156.20.16.8, Interface address 156.20.16.72      Backup Designated router (ID) 156.20.16.9, Interface address      156.20.16.73      Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5        Hello due in 00:00:09      Neighbor Count is 8, Adjacent neighbor count is 2        Adjacent with neighbor 156.20.16.8 (Designated Router)        Adjacent with neighbor 156.20.16.9 (Backup Designated Router)

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