From: Johnny Dedon (johnny.dedon@xxxxxxxxxx)
Date: Fri May 11 2001 - 17:37:54 GMT-3
Mohamed,
Responses inline
Johnny Dedon
Senior Staff Consultant
Exodus Professional Services
johnny.dedon@exodus.net
www.exodus.net
----- Original Message -----
From: "Mohamed Heeba" <MAHeeba@itqan.co.ae>
To: "'Johnny Dedon'" <johnny.dedon@exodus.net>; "Mohamed Heeba"
<MAHeeba@itqan.co.ae>
Cc: <ccielab@groupstudy.com>
Sent: Friday, May 11, 2001 3:12 PM
Subject: RE: Fatkid lab 502 ,expert redistribution
> well;
> i think things are more difficult than this ..let me share my ideas here
> i agree that the OSPF summary command is used to summarize the external
> routes INTO the OSPF domain ,however in some solutions out there ,it is
used
> to summarize the OSPF itself to other protocols like IGRP ,but this will
> work only if the subnets of the OSPF domain can be summarized at the IGRP
> subnet boundary ,also the summary route will be propagated into the OSPF
YOU HAVE TO HAVE A ROUTE TO CREATE THAT SUMMARY WITH AND IT MUST BE EXTERNAL
TO OSPF
> domain as E2 route which i wasnt able to filter it at all(or it will aslo
> disapear from the IGRP !!)
> wat u explained about the route feedback is another problem called black
> holes ( i hope im right in this ) ]
WHAT I TRIED TO EXPLAIN IS THE OSPF ROUTE WITH AN ADMINISTRATIVE DISTANCE OF
110 GETS DISTRIBUTED INTO IGRP WHERE IT GETS AND ADMINISTRATIVE DISTANCE OF
100. IF MUTUAL REDISTRIBUTION IS TAKING PLACE THEN THIS ROUTE WILL BE
REDISTRIBUTED BACK TO OSPF WHERE THE ROUTER WILL SEE THAT THIS ROUTE COMING
FROM IGRP HAS A LOWER ADMIN DISTANCE THAN THAT OF THE OSPF ROUTES AND
THEREFORE USE THIS ROUTE IN IT'S TABLE. IF YOU DO A SHOW IP ROUTE, THEN ALL
OF THE OSPF ROUTES THAT WERE DISTRIBUTED INTO IGRP AND THEN BACK WILL BE
LISTED AS E2. ANOTHER NOTE HERE IS THAT IN SOME CASES SPLIT HORIZON WILL
NOT ALLOW THE ROUTES BACK OUT OF IGRP SO THIS FEEDBACK DOES NOT OCCUR.
> where the routes of less admin distance will replace those of higher ones
> and the routes will stuck in one domain ...this problem will only happen
if
> u have TWO points of redistribution .
> AS per doyle , route feedback will happen when u have one point of
> redistribution and u do mutual redistribution from two domain one to the
> other ...doyle required to put filter in each domain to prevent this
> ....while without the filter things work fine with me ...that is why im
> confused ???
>
> DO I HAVE TO PUT FILTERS IF ONLY 1 REDISTRIBUTION ROUTER AND MUTUAL REDIST
> IS THERE ?? OR I NEED ONLY THIS WHEN I HAVE TWO POINTS OF REDIST.
IT IS GOOD PRACTICE TO FILTER ROUTES ANY TIME MUTUAL REDISTRIBUTION OCCURS.
IT IS ONLY NECESSARY WHEN REDISTRIBUTING FROM A HIGHER ADMIN COST TO A LOWER
ADMIN COST .
> secondly ,i didnt find anyway to summarize the OSPF 22 masks into the IGRP
> 24 domain without using either static routes or the summary address and
let
> the summary route propagate back to the OSPF domain ...
>
> any more ideas guys
> > -----Original Message-----
> > From: Johnny Dedon [SMTP:johnny.dedon@exodus.net]
> > Sent: Friday, May 11, 2001 1:01 PM
> > To: Mohamed Heeba
> > Subject: Re: Fatkid lab 502 ,expert redistribution
> >
> > Mohamed,
> > The summary route is used to summarize routes external to the ospf
process
> > for reditribution into the OSPF process. Have you looked at changing
the
> > mask on the link between igrp and ospf to a 22 bit mask ? Or have you
> > looked at sending a default route into igrp. Route feedback occurs when
> > you
> > redistribute ospf routes into igrp and since igrp has a lower admin and
> > the
> > routes are now igrp routes they get advertised back to the
redistributing
> > router where they get put in the route table as ospf external routes.
Get
> > it, they WERE ospf internal routes until you redistributed them to igrp
> > and
> > they got redistributed back. You should not allow this to happen. Use
> > route-maps or distribute list to stop this.
> > Johnny Dedon
> > Senior Staff Consultant
> > Exodus Professional Services
> > johnny.dedon@exodus.net
> > www.exodus.net
> > ----- Original Message -----
> > From: "Mohamed Heeba" <MAHeeba@itqan.co.ae>
> > To: <ccielab@groupstudy.com>
> > Sent: Friday, May 11, 2001 1:45 PM
> > Subject: Fatkid lab 502 ,expert redistribution
> >
> >
> > > guys ;
> > > i have a problem here which is similar to some post was here very
> > soon...
> > > it is regarding the redist of the OSPF into the IGRP ,here is my notes
> > and
> > > questions
> > > the case is :
> > > the ospf is having different masks of the network 135.1.x.x ,the masks
> > are
> > > /22
> > > ,/24,28 while the IGRP is only 24
> > > now i didnt get a clear answer about this question
> > > 1-does the summary address of the OSPF used to summarize the OSPF
domain
> > to
> > > other protocols or it is ONLY used to summarize the other protocols
> > domains
> > > into the OSPF ??
> > > i noticed that the summary address will NOT work until u redist IGRP
> > into
> > > the ospf process even before u redist the OSPF into the IGRP
> > >
> > > 2- how to redist the mask 22 in the IGRP ? it is not normal to
summarize
> > > this mask at the 24 boundary (i know this can be done to solve the
lab )
> > but
> > > the problem is that the OSPF will create a static route to the null0
in
> > the
> > > redist router and this will take all the traffic to null0 (since 24 is
> > more
> > > specific than the 22 in teh routing table
> > >
> > > 3- is the solution for this problem by using the area range command
> > > somewhere in teh OSPF domain
> > >
> > > 4-can someone define how the route feedback can heppen ?? becaue when
i
> > > tried to filter in the ospf domain the routes (to accept those only
> > coming
> > > from OSPF and not IGRP ,)teh summary disappeared from the route table
as
> > if
> > > it is coming from the IGRP
> > > i want to understand this point "is the route feedback means that the
> > > routes goes inside the domain to downstream routers and then come back
> > ,or
> > > it is only comes back on the redistribution router "
> > >
> > >
> > > i hope someone is patient to answer all this :)
> > > thx
> > > **Please read:http://www.groupstudy.com/list/posting.html
**Please read:http://www.groupstudy.com/list/posting.html
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