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How summarization OSPF

Hello guys I have a question about OSPF´s summarization.

For example: to summaraize the following net:

172.16.48.0 0.0.3.255
172.16.52.0 0.0.3.255
172.16.56.0 0.0.3.255

172.16.60.0 0.0.3.255

IN EIGRP in the interface configuration I use the command

R(config-if)#ip summarization eigrp 110 172.16.48.0 255.255.240.0

or IN STATIC

R(config)#ip route 172.16.48.0 255.255.240.0 serial 0/0

But how can I summarize this network or other in OSPF???

Thank!

3 REPLIES
Hall of Fame Super Blue

Re: How summarization OSPF

JulioUrena wrote:

Hello guys I have a question about OSPF´s summarization.

For example: to summaraize the following net:

172.16.48.0 0.0.3.255
172.16.52.0 0.0.3.255
172.16.56.0 0.0.3.255

172.16.60.0 0.0.3.255

IN EIGRP in the interface configuration I use the command

R(config-if)#ip summarization eigrp 110 172.16.48.0 255.255.240.0

or IN STATIC

R(config)#ip route 172.16.48.0 255.255.240.0 serial 0/0

But how can I summarize this network or other in OSPF???

Thank!

Julio

You use the area range command under the router ospf configuration ie.


router ospf 10

area 1 range 172.16.48.0 255.255.240.0

Jon

Hall of Fame Super Silver

Re: How summarization OSPF

Hello Julio,

OSPF can perform summarization of internal routes at area boundary on ABR nodes that connect area X to backbone area 0

router ospf 10

area X range 17216.48.0 255.255.240.0

external routes, that is the result  of redistribution into OSPF, including redistributed connected, cannot be summarized on area border but only by the ASBR node in the act of injecting these routes into OSPF domain.

For this reason a hierarchical network is required in OSPF and you need to think of the result for example of redistribute connected.

It is better to use network .. area + passive-interface instead of using redistribut connect, the first way we generate internal routes that can be summarized or filtered at area border.

see OSPF design guide

http://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a0080094e9e.shtml

being OSPF link state all routers within a single OSPF area need to have the same topological DB for this reason is not possible to summarize out an interface or to filter routes with distribute-list command (the effect of the command is in the IP routing table not on the OSPF LS DB this is tricky)

Hope to help

Giuseppe

Re: How summarization OSPF

Thank to answer my question, but I´m completing a practice that my teacher of CCNA assigme, so I´m using Packet tracer, and the last version of this software don´t accept this command:

router ospf 10

area X range 17216.48.0 255.255.240.0

There are other way in which I could summarize??

This is the network what I´m configurating, with some requeriments, but what I want is to make that OSPF redistribute the route to the Central Router and the Central redistribute to EIGRP as summarize.

Thank!

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