Date: Mon, 30 Sep 2002 12:36:21 -0400 From: Chuck Swiger <cswiger@mac.com> To: freebsd-isp@FreeBSD.ORG Subject: Re: Multihoming alternatives Message-ID: <C0A19920-D492-11D6-A6AC-000A27D85A7E@mac.com> In-Reply-To: <20020930155854.18500.qmail@linuxmail.org>
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On Monday, September 30, 2002, at 11:58 AM, Paul Keith wrote:
> First I would like to apologise if this is not the place for such
> questions.
> I am looking for links/tips/'intel' on building redundant/multihomed
> network that sits on a /29, (to serve webpages and mail to its clients on
> different AS's to produce proper redundancy), without resorting to BGP
> configurations or coloating with a large backbone.Is this possible?
In which case, your easiest bet is to run two data lines (DS-1's or
whatever) in a redundant topology from one provider. With Cisco routers,
I believe the term is "DHRP". The obvious problem is that if your
upstream provider goes down, you're out of service. However, you can
survive a failure of either data link or a local router, which covers
several probable failure modes.
Multihoming with two different network providers requires you to either
have a /20 and be globally routable (via ARIN, and yes, you'll have to do
BGP/EGP peering), or else you'll need to multihome your web server on
seperate IP networks from seperate providers.
DNS should round-robin the A records if you list several, but that still
isn't perfect, since dumb clients won't, but it's better than nothing.
Besides, if you do have a significant outage that will take at least hours
to fix, you can adjust your DNS to disable the downed IP.
> How will this DNS server run in a multihomed enviroment? Is it possible
> to load balance across 2 or 3 DNS servers or am I being silly?
Of course it's possible to load balance between multiple DNS servers; just
list multiple NS records for the zone. While it's okay to run DNS on a
multihomed box, you should not assume that a single machine with 2
interfaces is redundant. You should use several DNS servers, some offsite
or located with someone else's ISP.
-Chuck
Chuck Swiger | chuck@codefab.com | All your packets are belong to
us.
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"The human race's favorite method for being in control of the facts
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