From: Peter van Oene (pvo@usermail.com)
Date: Thu Oct 17 2002 - 10:33:25 GMT-3
At 11:10 AM 10/17/2002 +0800, Donny MATEO wrote:
>Ok I knew this one.
>Was getting an impression that there is a filter list for only type 3 LSA.
>
>Am I correct to assume that
>1. ip ospf database filter all out => will filter all LSA advertisement
>from this router and
>2. neigh x.x.x.x database filter all out => will filter all LSA
>advertisement to this neighbor ?
Use these commands at your own peril :) These are not here for route
filtering, but are tools for controlling flooding in networks where
parallelism in links exists. For example, if router A and router B are
connected one to another with multiple links, normally the same LSUs
containing the same set of LSAs would be flooded over each of those
links. This creates unnecessary flooding as the LSA information is
duplicated over N number of links. On can strategically use this command
to prune links from the flooding path to reduce the processing eaten up by
this duplicity (for example 1 of 2 parallel links could be used for
flooding). This concept is similar to the ISIS idea of "mesh groups"
However, if you don't have parallel links, you are going to mess up your
link state database and break your routing protocol.
>meaning you still can't specify which LSA type. If you're only asked to
>filter LSA type 3
>advertisement both wouldn't be applicable ?
>
>tks
>Donny
>
>
>
>
> aansar@sscomp.com
>
> .sg To: "Donny MATEO"
> <donny.mateo@sg.ca-indosuez.com>
> cc:
> ccielab@groupstudy.com, nobody@groupstudy.com
> 17-10-2002 10:43 Subject: RE: Filtering
> OSPF LSA type 3
>
>
>
>
>
>
>
>
>
>there is two commands
>1. ip ospf database filter all out (it is interface command)
>2. neighbor <x.x.x.x> database filter all out (remember this command
>requires the interface which connecting the neighbor to be multipoint
><ospf multi point interface>
>it is there in 12.1
>
>
>
>
> "Donny MATEO"
> <donny.mateo@sg.ca-ind To:
> ccielab@groupstudy.com
> osuez.com> cc:
> Sent by: Subject: RE:
> Filtering OSPF LSA type 3
> nobody@groupstudy.com
>
>
> 17-10-02 10:37 AM
> Please respond to
> "Donny MATEO"
>
>
>
>
>
>
>can't find this ospf filter-list command on 12.1(13).
>Can you tell me where this command is or does it require higher IOS version
>?
>
>Donny
>
>
>
> Senthil Kumar
>
> <senthil.kumar@intechno To: Peter van
>Oene <pvo@usermail.com>, Senthil Kumar
> logy.co.uk>
><senthil.kumar@intechnology.co.uk>, Dimitris Vassilopoulos
>
> Sent by:
><Dimitris.Vassilopoulos@eurodyn.com>, ccielab@groupstudy.com
>
> nobody@groupstudy.com cc:
>
> Subject: RE:
>Filtering OSPF LSA type 3
>
> 16-10-2002 21:12
>
> Please respond to
>
> Senthil Kumar
>
>
>
>
>
>
>
>you can filter lsa's with ospf filter-list
>
>-----Original Message-----
>From: Peter van Oene [mailto:pvo@usermail.com]
>Sent: 16 October 2002 14:06
>To: Senthil Kumar; Dimitris Vassilopoulos; ccielab@groupstudy.com
>Subject: RE: Filtering OSPF LSA type 3
>
>
>Keep in mind that you can't filter LSAs. You can filter routing
>information as it moves from the LSDB to the local routing table, but not
>the reception and publication of the LSAs to the LSDB. Filtering LSA
>reception would directly violate the specifications and likely lead to
>routing instability as SPF is only effective when everyone looks at the
>same topology.
>
>At 01:58 PM 10/16/2002 +0100, Senthil Kumar wrote:
> >true, but what if you want to filter some lsa-3 only..distribute list
>might
> >help when introduced on inbound routes at all peers.wont it?
> >
> >-----Original Message-----
> >From: Peter van Oene [mailto:pvo@usermail.com]
> >Sent: 16 October 2002 13:36
> >To: Dimitris Vassilopoulos; ccielab@groupstudy.com
> >Subject: Re: Filtering OSPF LSA type 3
> >
> >
> >All you can do here is use the totally stubby knob on the ABR(s). Once
>the
> >LSA is in the area, it is mandatory that all area resident routers receive
> >the LSA and correctly process it. Distribute-list in simply prevents any
> >relevant reachability information from making it to the local routing
> >table, but has no effect on LSA's.
> >
> >At 01:35 PM 10/16/2002 +0300, Dimitris Vassilopoulos wrote:
> > >Team,
> > >
> > >Cisco says in
> >
> >http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/12
>
> >2t/122t4/ftabrt3f.htm
> > >
> > >that if you want to filter OSPF type 3 LSA you have to run 12.2(4)T.
> > >I know that the image running in the lab is 12.1.x
> > >
> > >What if we're asked to filter inbound type 3 LSAs from a BB router?
> > >We must use " distribute-list x in " in EVERY ospf router ?
> > >
> > >Any comment on that would be appreciated...
> > >
> > >Dimitris
> >
> >________________________________________________________________________
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