Date: Fri, 4 May 2001 23:44:53 -0700 From: "Ted Mittelstaedt" <tedm@toybox.placo.com> To: "Kris Kirby" <kris@catonic.net> Cc: "Wai Chan" <waichan@hpu.edu>, <freebsd-net@FreeBSD.ORG>, <freebsd-questions@FreeBSD.ORG> Subject: RE: outgoing traffic load balancing with multiple ISP Message-ID: <005a01c0d52e$e3cc41c0$1401a8c0@tedm.placo.com> In-Reply-To: <Pine.BSF.4.21.0105050513170.23908-100000@spaz.huntsvilleal.com>
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Wai's problem isn't that he cannot load balance if he wanted to, because as you and I pointed out, once you have your own AS number you can do what you want. Wai's biggest problem is that ISP#1 sends all traffic to ISP#2. While Wai can set up so that both routes are equal cost to the NOC that ISP#2 is connected to, in effect he is competing with his own traffic on the link from ISP#2 to the rest of the world. For example (and keep in mind that Wai has not supplied bandwidth on his serial links so all this is speculation - one of the dangers of theorizing without sufficient information, as I've pointed out to certain people in this forum already) Suppose Wai has a T1 to ISP#1 and a T1 to ISP#2. When Wai's traffic is balanced, he can send 3Mbts to ISP#2. (1.5 directly and 1.5 routed through ISP#1) Sounds good - but only if ISP#2 has 3Mbts _available_ on ISP#2's connection to The World. In most of these scenarios, your going to find that ISP#2 is simply aggregating all it's customer traffic together and is running it's feeds to The World at 80% or more capacity. Thus, the larger that Wai's total bandwidth connection is into the combined network formed by ISP#1 and ISP#2, the less chance there is that he will realize any additional gain. My guess is that no matter how big that Wai makes the combined pipe to the network formed by ISP#1 and ISP#2, he's not going to realize any bandwidth gain past a certain level, a level that is probably somewhat below that of the pipe to ISP#2. Ultimately, like I was saying before Wai's best option if he is going to use ISP#2, is to do what is possible to reduce the money paid out to ISP#1. Frankly, it was a bad decision for Wai's net to plug into ISP#2 to begin with, but I'll give him the benefit of the doubt and assume that when they purchased bandwidth to ISP#2 that they wern't aware that ISP#1 was getting all of it's bandwidth from ISP#2. It would have been better from a use standpoint to plug into a completely separate network then get an AS number and do their own advertising. Ted Mittelstaedt tedm@toybox.placo.com Author of: The FreeBSD Corporate Networker's Guide Book website: http://www.freebsd-corp-net-guide.com >-----Original Message----- >From: Kris Kirby [mailto:kris@catonic.net] >Sent: Friday, May 04, 2001 10:18 PM >To: Ted Mittelstaedt >Cc: Wai Chan; freebsd-net@FreeBSD.ORG; freebsd-questions@FreeBSD.ORG >Subject: RE: outgoing traffic load balancing with multiple ISP > > >On Thu, 3 May 2001, Ted Mittelstaedt wrote: >> This gains ISP#1 multiple paths to ISP#2 - ie: More >> Bandwidth. Plus, it gives them a redundant backup in case their >> direct link to ISP#2 goes down. >> >> In exchange for this ISP#1 agrees to credit your bill to >> zero - in effect, you are now serving as a feed to them >> that costs them nothing. > >I'm going to veto that one. I've read (alas, I'm not yet a BGP admin) that >you can prepend your own AS as a method of equilization. As this scenario >unfolds, you have two pipes which eventually diverge. You prepend your AS >to the ISP #1 route (the big upstream) so that it's advertised as two >hops, and then route normally for the other ISP (the five-year contract >one). The net result should be two equal-cost routes back to your NOC even >though it goes to two ISPs (really one). > >Make sense? > >----- >Kris Kirby, KE4AHR | TGIFreeBSD... 'Nuff said. ><kris@nospam.catonic.net> | >------------------------------------------------------- >"Fate, it seems, is not without a sense of irony." > > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-net" in the body of the message
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