Faster 'Net growth rate raises fears about routers

David Schwartz davids at webmaster.com
Tue Apr 3 21:22:22 UTC 2001


Eric Hall wrote:

> Short-term the best hope for this is for businesses to put their boxes in
> colo farms or at an ISP with multi-homed networks in place. The problems
> start when customers try to multi-home from their HQ facility or from
> somewhere else that's isolated.
>
> Convincing customers that it is cheaper/better to put their main servers
> somewhere off-site away from them is the challenge. Otherwise more of
> them would do it.

	I've been in this situation as a consultant a few times, working with a
customer to evaluate multihoming versus other possible solutions. Generally,
colocation is in fact cheaper. It's cheaper to bring the server to the
bandwidth than the bandwidth to the server.

	Relibability is, of course, much less cut and dry. If you have the ability
to run your own network competently, multihoming adds a modicum of
protection against provider outages and misconfigurations. On the other
hand, if you have only one provider, you have (at least to some extent)
outsourced your network management and have someone else to go to if things
don't work. A single provider also has nobody else to point the finger at.

	One point worth stressing is that even if you have two links from your own
facility, they may fail in tandem due to telco/loop issues. On the other
hand, a high-end colocation provider is much more likely to have circuit
diversity across carriers and in disparate directions. In addition, scaling
bandwidth is generally easier at a colocation facility.

	For Internet access for human beings (not servers), there is no need for IP
addresses to remain static. So you can use NAT, DHCP, or proxies and change
providers reasonably easily. You can also use multiple concurrent providers
without having to BGP multihome (since you don't particularly care about any
given address being reachable from the outside in).

	If you need access both for servers and at an office, and it's all mission
critical, it's hard to argue for server colocation and two T1s to the
office. The problem is that this solution starts to get so complex that
multihoming seems simple by comparison. The benefit of not multihoming is
single-source responsibility -- lose that and there's almost no reason not
to multihome.

	Of course, there is no good way to address the risk of your provider going
out of business. Related issues include the provider suddenly sending you a
bill for about five times what you actually owe them and insisting that you
pay it in 8 days or they'll shut you off.

	I've also heard people say that it's more impressive to customers if we
have our own IPs, ASN,  etcetera (I hear that *way* too often). I've also
heard the argument that you want to be able to show your investors your
infrastructure. On the other hand, I've also heard "it'll really impress
people if we colocate at X because that's where Y colocates."

	The biggest problem I see is that the cost that a small company multihoming
places on everybody else isn't borne by the company. So when they ask, "why
shouldn't I multihome", it's hard to say, "because everyone else would
prefer that you don't".

	I think the best solution is to make it easier (on everyone) for people to
multihome with technological changes rather than to try to talk them out of
multihoming.

	DS





More information about the NANOG mailing list