nanog mailing list archives
Re: How Not to Multihome
From: "Bill Stewart" <nonobvious () gmail com>
Date: Tue, 9 Oct 2007 10:57:05 -0700
On 10/8/07, Keegan.Holley () sungard com <Keegan.Holley () sungard com> wrote:
That brings up an interesing point. My biggest fear was that one of my other customers could possible be closer to me that the ISP that provides the primary link and it would cause them to favor the backup link because of AS path. I think they are going to fight me on this and telling them to multihome to their original ISP would probably be frowned upon at this point. I was hoping that there was an RFC for multihoming that I could use to bail myself out.
What they're asking to do is really Just Fine. It may or may not accomplish what they want, depending on how they do it, e.g. whether traffic will go through their other ISP or yours. The main reason it's a Not Best Practice is that it often doesn't get what the user wants, e.g. the user only has a /29, so only the aggregate advertisement from their primary ISP works anyway, or it's PA space so they'll still have to give it up if they change ISPs. But if they've got a /24, that's big enough that most carriers will see it these days, and there's no need to clutter up the BGP ASN space if your user doesn't need the extra flexibility. There may even be a market for ISPs to do multihoming on a cabal basis, e.g. Carrier X and Carrier Y get a /20 that they assign routes from to customers that use both of them, but only advertise the aggregate to the rest of the net. They'd still need to handle the more specific routes internally and exchange them across their peering link, but wouldn't have to bother the rest of the net with that level of detail. -- ---- Thanks; Bill Note that this isn't my regular email account - It's still experimental so far. And Google probably logs and indexes everything you send it.
Current thread:
- Re: How Not to Multihome, (continued)
- Re: How Not to Multihome Justin M. Streiner (Oct 08)
- Re: IPv6 routes, was: How Not to Multihome Mike Leber (Oct 08)
- Re: IPv6 routes, was: How Not to Multihome Keegan . Holley (Oct 08)
- Re: IPv6 routes, was: How Not to Multihome William Herrin (Oct 08)
- Re: How Not to Multihome Keegan . Holley (Oct 08)
- Re: How Not to Multihome Justin M. Streiner (Oct 08)
- Re: How Not to Multihome Patrick W. Gilmore (Oct 08)
- Re: How Not to Multihome Justin M. Streiner (Oct 08)
- Re: How Not to Multihome Patrick W. Gilmore (Oct 08)
- Re: How Not to Multihome Brian Wallingford (Oct 08)
- Re: How Not to Multihome Bill Stewart (Oct 09)
- Re: How Not to Multihome Keegan . Holley (Oct 08)
- Re: How Not to Multihome Justin M. Streiner (Oct 08)
- Re: How Not to Multihome Patrick W. Gilmore (Oct 08)
- RE: How Not to Multihome Jamie Bowden (Oct 09)
- Re: How Not to Multihome Patrick W. Gilmore (Oct 09)
- Re: How Not to Multihome Justin M. Streiner (Oct 09)
- Re: How Not to Multihome Stephen Satchell (Oct 10)