North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Generally accepted announcement sizes
At Thursday 05:35 PM 6/22/00 , Tony Tauber wrote: >On Thu, 22 Jun 2000, Mike Heller wrote: > > > > Can anyone point me to a centralized resource for Tier 1 and Tier2 > > providers' accept policies? I have found that when some of my circuits go > > down various parts of the 'Net become unreachable and I attributed that to > > the size of that announcement being a /24. I assume that the carriers I'm > > having issue with are not using RADB as I registered all of my netblocks, > > >To find out exactly why your multi-homing set-up isn't working, >I'd work with your providers' operations staff. Perhaps set up >a time to test the fail over with them on hand to help you analyze >by looking at the routes on both. It should be possible for them >to help check the behavior of traffic over a third provider as well >if the providers are worth their salt. A rather complex setup on their side, as far as I can tell from route-server.cerf.net, route-views.oregon-ix.net and route-server.ip.att.net: iwon.com is AS 14829, and they seem to announce 3 networks: They announce 165.254.159.0/24 to AS 2914 (Verio) and AS 1785 (AppliedTheory) At the Oregon IX, the path via Verio is seen 15 times, via AT only 2 times. That's is an indicator of connectivity (and likely density of interconnectivity of providers to Verio vs. AT) right there. It's more balanced 5:4 (Verio:AT) at AT&T's route view. They announce 209.10.180.0 to AS 701 (UUnet), 4513 (PFM/Globix), 1239 (SL). At the Oregon IX, this is seen somewhat balanced between the 3, but at AT&T, it's 8 paths to UUNet or SL, only one path to PFM/Globix. They announces 216.73.19.128/25, which is solely seen through AS 2914 (Verio) at the Oregon-IX, and only 4 times at that. As expected, Verio seems to accept this as a customer route, but few of their peers accept the /25, Note that AT&T and CERF.net are not seeing this specific, but they see the larger /18 aggregate from AppliedTheory only, which is probably what 90% of all traffic to this network . It's a wonder that the /25 is seen at all: I think it should be withdrawn for sanity's sake. So, what exactly are you trying to accomplish, Mike? One thing is clear: the third network will always receive most traffic from AT, the second one mostly from UUnet+Sprint, the first one (which I believe you are referring to) mostly from Verio. The right way to overcome this is likely not to play with BGP toys like AS_prepend or making your providers manipulate the local_pref for you (and I see that Verio and UUnet don't seem to be crossing paths, at least for the first network listed), but by utilizing bigger networks: /22's in the >204.0.0.0/8 space are looking damn good in terms of 'being heard' compared to /24's. Did I mention that Verio seems to be the only one filtering at /20 boundary in 62/8 and 63/8 ? As a customer, you won't have that problem, obviously. bye,Kai
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