[176339] in North American Network Operators' Group
Re: Buying IP Bandwidth Across a Peering Exchange
daemon@ATHENA.MIT.EDU (Bill Woodcock)
Tue Nov 25 13:58:29 2014
X-Original-To: nanog@nanog.org
From: Bill Woodcock <woody@pch.net>
Date: Tue, 25 Nov 2014 10:56:06 -0800
To: NANOG <nanog@nanog.org>
In-Reply-To: <CAMDdSzPxnkC8ziu_Nidh741ZM6PUvmq7WojeA9TwU7VifiLwcQ@mail.gmail.com>
Errors-To: nanog-bounces@nanog.org
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On Nov 25, 2014, at 10:47 AM, Colton Conor <colton.conor@gmail.com> =
wrote:
> I know typically peering exchanges are made for peering traffic =
between
> providers, but can you buy IP transit from a provider on an exchange? =
An
> example, buy a 10G port on an exchange, peer 5Gbps of traffic with =
multiple
> providers on the exchange, and buy 5Gbps of IP transit from others on =
the
> exchange?
Some IXPs have a rule that explicitly disallows this, others encourage =
it, most don=92t care. I don=92t know of any that have a mechanism to =
enforce a rule prohibiting it.
PCH=92s guidance in the IXP formation process is to avoid creating rules =
which are, practically, unenforceable. So we generally counsel IXPs =
against having a rule precluding transit across the switch fabric. That =
said, a crossconnect is a _much better idea_. =20
> Some might ask why not get a cross connect to the provider. It is =
cheaper
> to buy an port on the exchange (which includes the cross connect to =
the
> exchange) than buy multiple cross connects. Plus we are planning on =
getting
> a wave to the exchange, and not having any physical routers or =
switches at
> the datacenter where the exchange/wave terminates at. Is this =
possible?
Yes, it=92s possible, but what you describe is a pretty fragile setup. =
Lots of common points of failure between peering and transit; places =
where screwing one up would screw both up. If all of this is really =
tangential to whatever you=92re doing, and you don=92t mind looking a =
little out-of-step with best practices, and you don=92t mind it all =
being down at once, any time anything breaks, then it may be a =
reasonable economy. If you=92re planning on actually depending on it, =
you need to do better engineering, and either spend more money, or =
allocate your money more conservatively.
Doing everything the cheapest possible way, regardless of the fragility =
or complexity, is very short-sighted, and is unlikely to be an economy =
in the long run.
-Bill
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