Command:

summary-address

Mode:

Router(config-router)#


Syntax:

summary-address address mask {level-1 | level-1-2 | level-2} prefix mask [not-advertise]
[tag tag]

no summary-address address mask {level-1 | level-1-2 | level-2}


Syntax Description:

address

Summary address designated for a range of addresses.

mask

IP subnet mask used for the summary route.

level-1

Only routes redistributed into Level 1 are summarized with the configured address/mask value. This keyword applies to IS-IS only.

level-1-2

The summary router is injected into both a Level 1 area and a Level 2 subdomain. This keyword applies to IS-IS only.

level-2

Routes learned by Level 1 routing will be summarized into the Level 2 backbone with the configured address/mask value. This keyword applies to IS-IS only.

prefix

IP route prefix for the destination.

mask

IP subnet mask used for the summary route.

not-advertise

(Optional) Used to suppress routes that match the prefix/mask pair. This keyword applies to OSPF only.

tag tag

(Optional) Tag value that can be used as a "match" value for controlling redistribution via route maps. This keyword applies to OSPF only.

 


Command Description:

Use the summary-address router configuration command to create aggregate addresses for OSPF. The no summary-address command restores the default.

Multiple groups of addresses can be summarized for a given level. Routes learned from other routing protocols can also be summarized. The metric used to advertise the summary is the smallest metric of all the more specific routes. This command helps reduce the size of the routing table.

Using this command for OSPF causes an OSPF autonomous system boundary router (ASBR) to advertise one external route as an aggregate for all redistributed routes that are covered by the address. For OSPF, this command summarizes only routes from other routing protocols that are being redistributed into OSPF. Use the area range command for route summarization between OSPF areas.


Example:

In the following example, summary address 10.1.0.0 includes address 10.1.1.0, 10.1.2.0, 10.1.3.0, and so forth. Only the address 10.1.0.0 is advertised in an external link state advertisement.

Router(config-router)#summary-address 10.1.0.0 255.255.0.0

Misconceptions:
None

Related commands:
area
ip ospf authentication-key

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