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Re: "John W. Stewart III": Re: Routing for Internet World's Fair
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if WIDE does want to do this, this note describes how to do it

the situation is that we hear it from the railroad with an AS path of "6204 4690" and from WIDE with an AS path of "2500 4690". since both WIDE and the railroad are customers, the local_pref for both is 100. that means that we will do closest exit and the western half of our net will use WIDE while the eastern half will use the railroad. what needs to be done is local_pref the WIDE route(s) to 90 so that all traffic to that AS goes through the railroad

we implement routing policies like this by having the customer tag the routes with a special bgp community. bgp communities work in cisco version 10.3

sample syntax on the WIDE router would be:

router bgp 2500 neighbor 204.70.32.13 remote-as 3561 neighbor 204.70.32.13 send-community neighbor 204.70.32.13 route-map set-community

ip as-path access-list 25 permit 4690

ip as-path access-list 1 permit .*

route-map set-community permit 10 match as-path 25 set community 0x0DE9005A route-map set-community permit 20 match as-path 1

this results in WIDE setting the 0x0DE9005A community (which is 3561 in the high-order two bytes and 90 in the low-order two bytes) on routes with 4690 in the AS path, but doing nothing special with other routes. when MCI sees the routes with the special community, we will set local_pref to 90

is this clear?

/jws

> > Could the Japanese team please contact WIDE to tell MCI that MCI > should prefer AS4690 from AS6204 rather than from AS2500... > > -Marten > > ------- Forwarded Message > > Date: Wed, 24 Jan 1996 17:24:27 -0500 > From: "John W. Stewart III" <jstewart@mci.net> > To: Marten Terpstra <marten@BayNetworks.com> > cc: rr-types@mci.net > Subject: Re: Routing for Internet World's Fair > > > marten, > > this has to be worked from the other direction. the special > config we support is for treating certain routes as backup; > we local-pref routes down, not up. so WIDE will need to > contact us and work out how to treat [at least] this network > as backup through them. we actually have a pretty cool way > to do it with bgp communities > > this will be the case for all nets which don't otherwise work > correctly by default (e.g., if as-path or whatever doesn't > already Do The Right Thing) > > /jws > > > > > Hi folks, > > > > you may be aware that we are setting up this network for the Internet > > World's Fair. We currently have connectivity to Japan over a private > > T3 and we are announcing AS4690 to you at WTN, DC (mix1 I guess you > > call that router). However, you get the same route through WIDE in > > SF. Could you weigh our announcement over WIDE's announcement for > > AS4690? > > > > >From AS3561: > > > > as-in: from AS2500 100 accept AS-WIDE > > as-in: from AS6204 100 accept AS-EXPO > > > > as-macro: AS-WIDE > > as-list: AS2508 AS2515 AS2520 AS2523 AS2528 AS4690 > > ^^^^^^ > > as-macro: AS-EXPO > > as-list: AS6204 AS6205 AS3920 AS4690 > > ^^^^^^ > > > > As far as I am concerned, you can weigh our complete peer better or > > just this one AS. Your decision. However, since we will get some more > > connections throughout the place, some of the other ASes may show up > > from different places as well. The exit to WTN will always be our > > primary exit for AS-EXPO though..... > > > > Thanks much! > > > > -Marten > > > > PS Could you please verify that I am indeed announcing the one network > > in AS4690, 133.246/16? > > > > ------- End of Forwarded Message >

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