From: Joseph D. Phillips (josephdphillips@fastmail.us)
Date: Sun Jul 25 2004 - 02:53:41 GMT-3
Such as? :)
That's an interesting problem. So you're saying without the ip route for
a NAT pool to null 0, the route won't propagate to a BGP peer? Or is
that what Solie & Lynch are saying?
On Sun, 25 Jul 2004 01:22:49 -0400, "Brian Dennis"
<bdennis@internetworkexpert.com> said:
> If they are being nice they would let you use a static route but there
> are other methods to advertising a NAT pool.
>
> Brian Dennis, CCIE #2210 (R&S/ISP-Dial/Security)
> bdennis@internetworkexpert.com
> Internetwork Expert, Inc.
> http://www.InternetworkExpert.com
> Toll Free: 877-224-8987
> Direct: 775-745-6404 (Outside the US and Canada)
>
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> Larry Metzger
> Sent: Saturday, July 24, 2004 10:03 PM
> To: 'group study'
> Subject: RE: Using ip route to null 0 to advertise local network to BGP
> peer
>
> For clarification....
> The example that you are referring to is using NAT and the route to
> null 0 is for the placement of a route to an address that otherwise does
> not exist. I haven't taken my exam yet, but I will venture to guess
> that this would be allowed if the situation was using NAT.
>
> What would you say in this case???
>
> Larry
>
> -----Original Message-----
> From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
> James
> Sent: Saturday, July 24, 2004 8:44 PM
> To: Joseph D. Phillips
> Cc: group study
> Subject: Re: Using ip route to null 0 to advertise local network to BGP
> peer
>
> On Sat, Jul 24, 2004 at 08:12:37PM -0700, Joseph D. Phillips wrote:
> > I notice in a couple places, Karl Solie and Leah Lynch, in CCIE
> > Practical Studies II, use a static route to null 0 in order to make
> sure
> > that a local network advertises properly to a BGP peer.
>
> What Karl and Leah had done is mostly done in real-world environment,
> where it
> is recommended that an AS always null-route w/ high A.D. their aggregate
> to
> prevent route-looping up to whomever they have default-route or less
> specific
> route pointed to (also to stabilize their BGP announcements when their
> internal
> IGP or connected interfaces holding the announced routes begin
> flapping). This
> seems like to be a BCP amongst most people doing BGP.
>
> > For example, on page 805, there is an explicit advertisement of the
> > 191.19.42.0/24 net within BGP, and just to be on the "safe" side, they
> > added: ip route 191.19.42.0 255.255.255.0 null0 253
> >
> > I understand the need for a high administrative distance on the static
> > route, but is this kind of route allowed in the lab exam?
>
> Since it is statically/manually configured, IMHO it constitutes static
> route.
> So I think it is safer to stay away from doing that in lab unless you
> are
> permitted to do so.
>
> >
> > Is it one of those real world things we're not allowed to do on lab
> day?
>
> Sounds like it. :)
>
> Since BGP scans rib before announcing a prefix, the only course of
> action w/o
> null route is probably to create loopbacks and assign addrs there..
>
> -J
>
>
> --
> James Jun TowardEX
> Technologies, Inc.
> Technical Lead Network Design, Consulting, IT
> Outsourcing
> james@towardex.com Boston-based Colocation & Bandwidth
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>
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