I agree with Bill...going it on the cheap is risky. DOn't consider it for primary. It may be good for backup. I have sold small amounts of transit to non-ISP companies on exchanges (100-200 meg). It's a good extra backup for ISPs, if you setup your local pref, MED and then prepend your AS an extra time or two to the prefixes you transmit. Then if you ever need to use it, it's sitting there waiting to send and receive traffic. I let ISPs customers do that with us for real low cost backup fees. Bob Evans
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 dont care. I dont know of any that have a mechanism to enforce a rule prohibiting it.
PCHs 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_.
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, its 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 youre doing, and you dont mind looking a little out-of-step with best practices, and you dont mind it all being down at once, any time anything breaks, then it may be a reasonable economy. If youre 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