From: Darek Kuzma (darekk@xxxxxxxxxxxxx)
Date: Mon May 21 2001 - 08:06:28 GMT-3
Mark,
I think that your are right. RTA will not advertise "prepended" 192.68.11.0 bac
k to RTF as it
will learn better route from RTF.
Anyway Halabi uses the same logic on the page 331 to explain why RTA sees only
one route to
192.68.11.0 (before prepending).
Thanks,
Darek
mcaplan.cs@clearstream.com wrote:
> Has anyone tested Halabi's scenarios, and confirm an observation of mine
>
> I'm doing AS_Path manipulation with the same config as pg 332. The diagram
> of the network is on pg326. He says that when the prepend route map is added
> to RTC, that RTF should see 2 routes to network 192.68.11.0 - one via RTC,
> the other via RTD.
>
> ie
>
> *> 192.68.11.0 192.68.5.2 0 2 1 i
> * i 172.16.20.1 0 100 0 1 1 1 i
>
> This doesn't work out in my network, and I dont think it should. This is
> what I get for the BGP table on RTF
>
> Network Next Hop Metric LocPrf Weight Path
> * i172.16.1.0/24 172.16.2.254 0 100 0 i
> *> 0.0.0.0 0 32768 i
> * i172.16.10.0/24 172.16.2.254 11 100 0 i
> *> 0.0.0.0 0 32768 i
> * i172.16.65.0/26 172.16.2.254 11 100 0 i
> *> 0.0.0.0 0 32768 i
> *>i172.16.220.0/24 172.16.2.254 0 100 0 i
> *> 192.68.10.0 192.68.5.2 0 0 2 i
> *> 192.68.11.0 192.68.5.2 0 2 1 i
>
> RTF only sees the one route via RTD. This makes sense because RTF advertises
> this route to RTA, which becomes a better route for RTA. so RTA wont
> advertise the route with the prepended AS.
>
> RTA's BGP routing table shows:
>
> *>i192.68.11.0 172.16.1.2 100 0 2 1 i
> * 172.16.20.1 0 0 1 1 1 i
>
> Can anyone confirm my logic here or have I done something different to
> Halabi's config
>
> Thanks
>
> Mark
>
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