Creating a Range of OSPF Interfaces

To create a range of OSPFv2 interfaces:

1. Create an OSPF routing process.
2. Create the range of IP addresses associated with the routing process and the corresponding OSPF interfaces.
3. Assign an area ID associated with each range of IP addresses.

Each router running OSPFv2 has a database describing a map of the routing domain. This map needs to be identical in all participating routers.

network area

• Use to configure a range of OSPFv2 interfaces and their related area.
• If the specified range matches one or more of the IP addresses configured for IP interfaces, one or more corresponding OSPF interfaces are created and placed in the specified area.
• Create address ranges that do not overlap; you can attach only the same range of interfaces to a single area.
• You cannot use this command for unnumbered interfaces.
• If the range specified by this command includes an address on an interface that is being referred to by unnumbered interfaces, all of the unnumbered interfaces begin trying to form adjacencies. If this behavior is not intended, you must reevaluate the interface assignment or the range specified by the command.
• Example 1—shows the creation of one OSPF interface in the backbone area

  host1(config-if)#ip address 2.2.2.1 255.255.0.0

  host1(config-if)#ip address 2.2.1.1 255.255.0.0 secondary

  host1(config)#router ospf 2

  host1(config-router)#network 2.2.2.0 0.0.0.255 area 0

• Example 2—shows the creation of two OSPF interfaces, one in the backbone area and one in a non-backbone area

  host1(config-if)#ip address 2.2.2.1 255.255.255.0

  host1(config-if)#ip address 2.2.1.1 255.255.255.0 secondary

  host1(config)#router ospf 2

  host1(config-router)#network 2.2.2.0 0.0.0.255 area 0

  host1(config-router)#network 2.2.1.0 0.0.0.255 area 1

  This sequence of commands creates two OSPF ranges (2.2.2.0/24 and 2.2.1.0/24), with each range belonging to a different area. Area 0 is configured for 2.2.2.0/24, and area 1 is configured for 2.2.1.0/24. This sequence also creates two OSPF interfaces: one in the backbone area (area 0) using IP address 2.2.2.1, the second in a nonbackbone area (area 1) using IP address 2.2.1.1. This command also creates the two areas if they do not already exist.

• Use the no version to delete OSPF interfaces, ranges, and areas.

  Note: Until you activate the configured network range for summaries by issuing the area range command, the range is not active for summarization; the network range is summarized through area summaries—for ABRs only. (See Aggregating OSPF Networks .) The only range that is active by default if you do not issue the area range command is the network that matches the IP interface’s network exactly. (In other words, by default the exact network of the IP interface is going to be summarized into other areas.)

• See network area

ospf enable

• Use to enable OSPF on the router.
• OSPF is enabled by default.
• Example

  host1(config-router)#ospf enable

• The no version of this command is deprecated and may be removed in a future release. Use the ospf shutdown command to disable OSPF on the router.
• See ospf enable

router ospf

ipv6 router ospf

• Use to set an OSPF process ID.
• The process ID can be any positive integer in the range 1–65535.
• You must assign a unique ID for the OSPF routing process.
• From a virtual router context you can specify a VRF name (OSPFv2 only). Doing so changes the context to that of the specified VRF and remains so until you exit from the OSPFv2 router context.
• Example 1

  host1(config)#router ospf 5

• Example 2

  host1(config)#ipv6 router ospf 5

• Use the no version to end the designated OSPF routing process.
• See router ospf
• See ipv6 router ospf

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