From: Jonathan V Hays (jhays@jtan.com)
Date: Sun Sep 28 2003 - 11:20:59 GMT-3
The "distance" command is good for fault tolerance and it is good for
forcing the router to prefer the native routing protocol. But it may not
prevent routing loops, depending on the network topology. Even with the
distance command working properly you may still have to filter with
distribution lists or route-maps.
In the ASCII diagram below, we can suppose that mutual redistribution
between different routing protocols is taking place on R2 and R3, and
perhaps R4 also. Using "distance" to force each router to prefer its
native routing protocol in the routing table is still not going to stop
routes from being forwarded in a loop.
R1
/\
/ \
R2--R3
\ /
\/
R4
I think the thing to learn is that when it comes to redistribution on
the CCIE Lab exam, you cannot simply memorize a technique and use it
every time. Each situation is different.
Jonathan
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
navaid@rogers.com
Sent: Sunday, September 28, 2003 9:45 AM
To: info@mpauli.de; chipn@intraworx.net
Cc: ccielab@groupstudy.com
Subject: Re: Re-3: Mutual redistribution.
Marcus,
Thanks for reply.
I think "distance 120 150.100.1.253 0.0.0.0 10" will help me with RIP
and OSPF. What about EIGRP ?
Another question is that: Do I need to do this even if there is only one
redistribution point.
Thanks,
Navaid
>
> From: info@mpauli.de
> Date: 2003/09/28 Sun AM 08:46:16 EDT
> To: navaid@rogers.com,
> chipn@intraworx.net
> CC: ccielab@groupstudy.com
> Subject: Re-3: Mutual redistribution.
>
> Hi Navid,
>
> well I'm not using this technique via route-map but via distance, here
is an example:
>
> router rip
> version 2
> passive-interface Serial0/0
> passive-interface TokenRing0/0
> passive-interface Loopback0
> network 133.10.0.0
> network 150.100.0.0
> neighbor 150.100.1.253
> distance 255
> distance 120 150.100.1.253 0.0.0.0 10
> distance 120 150.100.1.254 0.0.0.0 20
> !
> access-list 10 remark Permit only 192.177.ODD].0/24
> access-list 10 permit 192.177.1.0 0.0.254.255
> access-list 10 permit 10.0.0.0 0.255.255.255
> access-list 20 remark Permit only 192.177.[EVEN].0/24
> access-list 20 permit 192.177.0.0 0.0.254.255
> access-list 20 permit 10.0.0.0 0.255.255.255
>
> Hope I could help...
>
> Cheers
> Marcus
>
>
> -------- Original Message --------
> Subject: Re: Re: Mutual redistribution. (28-Sep-2003 14:30)
> From: navaid@rogers.com
> To: cbsnow31@yahoo.com
>
> > Chris,
> > you suggested to use route-map to drop AD. Where this route-map will
be
> > applied ?
> >
> > Navaid.
> >
> > >
> > > From: christopher snow <cbsnow31@yahoo.com>
> > > Date: 2003/09/28 Sun AM 07:12:02 EDT
> > > To: chipn@intraworx.net
> > > CC: ccielab@groupstudy.com
> > > Subject: Re: Mutual redistribution.
> > >
> > > Doyle covers this in TCP/IP Vol I very well in the
> > > redistribution section. I have adopted his method and
> > > it works every time. He uses the distance command and
> > > sets both protocols above their normal distance...
> > > i.e. if you were doing EIGRP and OSPF set both
> > > protocols at 130. Then use route maps to drop the
> > > selected routes back to their normal distance within
> > > each protocol. This prevents route feedback and
> > > establishes redundancy if you have more than one point
> > > of redistribution.
> > >
> > > HTH
> > >
> > > Chris Snow
> > >
> > > --- chipn@intraworx.net wrote:
> > > > I'm looking for opinion on lab strategy.
> > > >
> > > > If you encounter a mutual redistribution scenario
> > > > with multiple
> > > > redistributions points on the lab, would it be in
> > > > your best interest to
> > > > explictly control your routing information to
> > > > prevent route feedback? It
> > > > is possible to have complete connectivity in this
> > > > scenario without
> > > > filtering, but still have the potential for routing
> > > > loops.
> > > >
> > > > I thought this would be the best place to get some
> > > > expert advice on the
> > > > subject.
> > > >
> > > > Thanks.
> > > >
> > > > ***Get your CCIE and a FREE vacation:
> > > > Shop.GroupStudy.com***
> > > >
> > >
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