From: Howard C. Berkowitz (hcb@xxxxxxxxxxxx)
Date: Sat Jun 01 2002 - 15:54:34 GMT-3
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
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