From: Kevin Baumgartner (kbaumgar@xxxxxxxxx)
Date: Tue Jan 23 2001 - 17:06:07 GMT-3
Good point, and if you have split-horizon defined on the igrp router
this should prevent the advertisement back to OSPF. You however may not
be allowed to define split-horizon so this sounds like a reasonable way of
preventing a routing loop.
Really guess it depends what is allowed. Turning on split-horizon
seems the easiest, but the easiest isn't always what gets asked.
Kevin
At 07:41 PM 1/23/01 +0000, Robert DeVito wrote:
>Shouldn't split-horizon take care of the problem of IGRP advertising OSPF
>routes back into OSPF?
>
>Robert
>
>
>----Original Message Follows----
>From: SherefMohamed@cdh.org
>Reply-To: SherefMohamed@cdh.org
>To: "Connary, Julie Ann" <jconnary@cisco.com>
>CC: ccielab@groupstudy.com, nobody@groupstudy.com
>Subject: Re: summary-address in ospf and redistribution
>Date: Tue, 23 Jan 2001 09:55:22 -0600
>
>You need to do mutual redistribution between OSPF and IGRP,
>the idea is to not allow IGRP send back to OSPF the summary address !
>Here is how I will do it:
>
>!
>router igrp 2
>..........
>distribute-list 10 out ospf
>..........
>!
>router ospf 1
>...........
>distribute-list 11 out igrp
>...........
>!
>
>access-list 10 deny 170.10.2.0 0.0.0.255
>access-list 10 permit 0.0.0.0 255.255.255.255
>!
>access-list 11 permit 172.10.2.0 0.0.0.255
>access-list 11 deny 0.0.0.0 255.255.255.255
>
>Please test it & tell me how it works !
>
>Thanks
>Sheref
>
>
>
>
>
> "Connary,
> Julie Ann" To: ccielab@groupstudy.com
> <jconnary@cis cc:
> co.com> Subject: summary-address in
>ospf and redistribution
> Sent by:
> nobody@groups
> tudy.com
>
>
> 01/23/2001
> 08:37 AM
> Please
> respond to
> "Connary,
> Julie Ann"
>
>
>
>
>
>
>Hi All,
>
>I ran across a practice lab and another fat-kid lab that use the ospf
>summary-address to overcome
>vlsm to fsm issues when redistributing ospf into igrp:
>
>
>
>situation: The ospf connected interface has a longer mask than the IGRP
>connected interface.
> area-range does not work because it is on the same
>router.
>
> The Fatkid lab - expert redistribution - solves this with a
>summary-address.
>
>Question - does this not inject E2 routes back into your OSPF domain?
>
>
>OSPF area 2
>170.10.128.4 - 255.255.255.192
>|
>|
>|
>R4 -----------IGRP - 170.10.2.4 255.255.255.0
>
>To redistribute the ospf interface into IGRP a summary-address is
>used: summary-address 170.10.128.0 255.255.255.0
>
>But then in the ospf domain you get an E2 route to 170.10.128.0 in your
>ospf domain.
>
>So how do you prevent this E2 route into OSPF - can you filter it?
>
>Thoughts?
>
>remember - no static, no default.
>
>Julie Ann
>
>
>
>
>------------------------------------------------------------------------
> Julie Ann Connary
> | | Network Consulting Engineer
> ||| ||| Federal Support Program
> .|||||. .|||||. 13635 Dulles Technology Drive,
>Herndon VA 20171
> .:|||||||||:.:|||||||||:. Pager: 1-888-642-0551
> c i s c o S y s t e m s Email: jconnary@cisco.com
>
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>
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