From: Joe Jia (ellenjjl@xxxxxxxxxx)
Date: Mon Jun 03 2002 - 21:01:54 GMT-3
Hi,
This link maybe useful?
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122
t/122t4/ftbgpri.htm
----- Original Message -----
From: "Nigel Taylor" <nigel_taylor@hotmail.com>
To: <ccielab@groupstudy.com>
Sent: Saturday, June 01, 2002 6:44 PM
Subject: Re: BGP conditional Advertisement
> Nick,
> I understand what it is you're trying to accomplish by trying to
> find another way to perform BGP conditional route advertising.
> However, as Howard points out the question would be why? I've looked at
the
> scenario you've posted and based on the information
> you provided, I don't see how we can get the BGP process in RtrC to
> conditionally source the Y/24 network, without some type of
> tracking of routes in the BGP table. You mentioned the goal is to
> accomplish this without specifically using the
> "advertise-map & non-exist-map" neighbor command. The only other options
> left would be using filter-list, distribute-list, and route-maps
> which would be static configurations.
>
> I did some thinking and it came to me that maybe the only other way I
could
> think of to accomplish this would be to, identify the X/24 route being
> received from RtrA at RtrC using a route-map and setting a community
string
> on the X/24 route. Then under the bgp process of RtrC you could
> use the "network" command with a "route-map" to set another community
string
> for the Y/24 route. Lastly you could set and outbound route-map
> to RtrB(on RtrC) using the 'no-advertise" attribute to filter the Y/24
route
> based on if the X/24(community) route is present or not.
>
> Nigel
>
>
> ----- Original Message -----
> From: "Howard C. Berkowitz" <hcb@gettcomm.com>
> To: <ccielab@groupstudy.com>
> Sent: Saturday, June 01, 2002 2:54 PM
> Subject: Re: BGP conditional Advertisement
>
>
> > At 7:08 PM +1000 6/1/02, Nick Shah wrote:
> > >Nigel,
> > >
> > >All routers are running in different AS's
> > >
> > >No IGP's running between all of the 3 routers.
> > >
> > >X/24 is being originated from RtrA
> > >y/24 is to be *conditionally * originated by RtrC (if RtrC stops
> receiving
> > >X/24 from RtrA)
> >
> > I, too, don't quite have enough detail to give a definitive answer,
> > particularly as to where y/24 is and how router C knows about it.
> >
> > What is the address relationship between x and y? What problem are
> > you trying to solve? This doesn't seem a plausible backup scenario,
> > unless y is an alternate address that will be tried in recovery by a
> > host connected to rtrB.
> >
> > Approaches that might be considered include making the next hop in C
> > for y primarily dependent on the reachability of a next hop in A.
> > Another approach might be to use outbound route filtering in B to C,
> > in which B tells C not to advertise y as long as it is receiving x
> > originated by A.
> >
> > >
> > >thanks
> > >Nick
> > >-----Original Message-----
> > >From: Nigel Taylor <nigel_taylor@hotmail.com>
> > >To: ccielab@groupstudy.com <ccielab@groupstudy.com>
> > >Date: Saturday, 1 June 2002 3:43
> > >Subject: Re: BGP conditional Advertisement
> > >
> > >
> > >>Nick,
> > >> I have a couple of questions?
> > >>
> > >>1. What AS's are the 3 routers in? could you be more specific.
> > >>2. The X and Y routes where do they originate? both from RtrA, X from
> > >RtrA,
> > >>Y from RtrC?
> > >>3. Are there any IGPs running between all the routers.
> > >>
> > >>Nigel
> > >>
> > >>----- Original Message -----
> > >>From: "Nick Shah" <nshah@connect.com.au>
> > >>To: <ccielab@groupstudy.com>
> > >>Sent: Friday, May 31, 2002 11:11 PM
> > >>Subject: BGP conditional Advertisement
> > >>
> > >>
> > >>> Guys,
> > >>>
> > >>> I am trying to achieve a behaviour similar to BGP conditional
> > >>advertisement
> > >>> *without* using non-exist-map and/or advertise-map. Basically ...
> > >>>
> > >>> RtrA ------- RtrC-----------RtrB
> > >>>
> > >>> RtrA advertises route X/24 to RtrC under normal circumstances, when
> RtrC
> > >>is
> > >>> receiving X/24 from RtrA it suppresses the advertisement of Y/24
> (doesnt
> > >>> advertise) to RtrB.
> > >>> But if RtrA stops sending prefix X/24 to RtrC, RtrC starts sending
> Y/24
> > >to
> > >>> RtrB.
> > >>>
> > >>> All this to be done *without* using advertise-map & non-exist-map
> > >>>
> > >>> Ideas..
> > >>> Nick
This archive was generated by hypermail 2.1.4 : Tue Jul 02 2002 - 08:12:20 GMT-3