From: Alexander Arsenyev (GU/ETL) (alexander.arsenyev@ericsson.com)
Date: Wed Jan 19 2005 - 13:39:47 GMT-3
Depending on what You are trying to accomplish and 6500 supported features You could have
only summary routes in Campus A/B 6513 route table and no specifics
(but OSPF LSA database have all routes, summary and specifics).
Here is the algorithm :
1. Assign a secondary IP address to one of Campus A 6513' interfaces:
"ip add 10.149.254.254 255.255.0.0 secondary"
Don't worry, Your traffic to 10.149/16 won't be blackholed because Campus A 6513 and 6509 will have summary and specific routes, specific taking precedence due to shorter mask length.
2. Include it in OSPF process
"network 10.149.0.0 0.0.255.255 area 0"
3. On Campus B 6513' filter inbound all specific routes in 10.149/16 range with "distribute-list route-map"
http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/120limit/120s/120s24/routmap.htm
Disclaimer: I don't know if this feature is available in 6500 at all. I tested it on 7507 and it appears to work fine.
4. Repeat steps 1-3 for Campus B.
Steps 1-2 could also be accomplished with static route to Null0 and redistributing it into OSPF. This approach could actually be more appropriate if You have traffic going to Campus A non-existing subnets in 10.149/16 range. Instead of being sent out the interface with secondary address it will be dropped.
As a side note the 10.149.5.0/23 has wrong netmask, it is a host address, not subnet address.
Comments anyone?
HTH,
Cheers
Alex
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com]
Sent: 18 January 2005 22:34
To: Richard Anderson; ccielab@groupstudy.com
Subject: RE: OSPF Summarization
Richard,
No. All routers in the link state area must have the same copy
of the link state database. This implies that summarization and
filtering can only occur on area boundaries or autonomous system
boundaries.
Brian McGahan, CCIE #8593
bmcgahan@internetworkexpert.com
Internetwork Expert, Inc.
http://www.InternetworkExpert.com
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> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf
Of
> Richard Anderson
> Sent: Tuesday, January 18, 2005 4:00 PM
> To: ccielab@groupstudy.com
> Subject: OSPF Summarization
>
> Is it possible to summarize OSPF networks eventhough all the networks
are
> in
> area 0
>
>
> For example,
>
> I have three two campuses seperated by 6509 router.
>
> Campus A has its own 6513 layer III router switch, and has about 40
> subnets
>
> 10.149.2.0/23, 4.0, 5.0 and so on.
>
> Campus B has its own 6513 layer III router switch, and has about 40
> subnets
>
> 10.159.2.0/23, 4.0, 5.0 and so on.
>
> Everything is under area 0, and I wanted to summarize both the
networks at
> 6513s so it will only announce
> network 10.149.0.0/16 and 10.159.0.0/16 to 6509s respectively.
>
> Regards,
>
> Richard.
>
>
This archive was generated by hypermail 2.1.4 : Wed Feb 02 2005 - 22:10:24 GMT-3