an over-the-top data center

Jean-François Mezei jfmezei at
Mon Dec 1 23:14:08 UTC 2008

patrick at wrote:

> The Internet can be mission critical.  (Well, not really, but it's =20
> trying.)  And for something mission critical, a single point, no =20
> matter how well reinforced, is not good enough.

It may not be "mission critical" for any one particular client, but when
you bundle all of the separate non critical applications on the net, the
 impact of downtime on the population becomes important enough to be
seen as "critical".  Think about airlines expecting passengers to
check-in via the internet more and more so that they can reduce staff at

> The exchange point should _NOT_ be mission critical.  As I explained =20
> multiple times in the thread, if that is your only vector, your design =20=
> is broken.  Period.  Care to argue otherwise?

Fair enough. However, in a particular city, you may have difficulty
finding multiple different transit providers whose fiber trunks are
truly differently routed. It is bad enough that different transit
providers may share the same dark fibre cable out of the city.

Very large cities such as New York may make it much easier to find truly
independant transit links. But for small, medium cities, it becomes
harder (especially if geography limits the number of truly separate links).

In the end, to form a truly redundant service, you probably need to have
a presence in multiple cities, each with its own carrier hotel. And at
that point, each carrier hotel need not be "mission critical" because
you can continue service from another city.

But even if you have backup, you still want the carrier hotels to be
robust.  And if you can't afford to have data centres/networks in
different cities, you do want to have a robust interconnect to the
internet. Consider the number of small/medium size ISPs whose
infrastructrure is located at the carrier hotel where the local exchange
resides. To them, the availability of services at that carrier hotel is
mission critical because their bueiness depends on it, and they can't
afford to be in multiple locations.

More information about the NANOG mailing list