Hello,
I'm looking at deploying "POPs" at several IDCs across the globe.
Each POP will contain several servers. (At most ten.) I would like each POP
to use the same set of IP addresses; connections to these IP addresses will
get to the nearest POP by virtue of routing.
IOW, I think I'm wanting to have all my POPs belong to one AS, as if said
AS multi-homes to each POP/IDC, except that the multi-homing is virtual,
because I don't have links from my "enterprise network" to these IDCs.
(Well, I don't expect to have much of an enterprise network. 
Are there providers of such? Will I be able to get a globally routable IP
block for my AS? Or is my best bet to pick one provider which has global
presence? (Which such global providers are there? Do people like Exodus or
Digital Island count?)
TIA for your input. Cheers.
Your biggest problem will be getting address space, for that few servers,
that is globally routable. Your other issue, is getting transit from
multiple carriers - an Equinix or PAIX is your best bet for this sort of
thing.
What you are describing can be done, BGP-wise in two way. One way is to have
discrete address space for each POP, and run discontiguous eBGP, using the
same AS in each POP. To defeat bgp loop detection, and ensure each POP is
reachable from the others, you need a default route point towards your
transit providers.
The other popular method for doing this, is running Confederation BGP, with
each POP as a sub-AS, and GRE tunnels between POPs.
I personally prefer #1, but it's harder from the IP addressing angle. Both
work, and work well. You will need to announce a larger aggregate out, at
least one POP, of /20 or above, to deal with the few ISPs that filter on
those boundaries. If at least one of your ISPs is the same in each location,
you can limit some of the sub-optimal routing that might result.
- Daniel GOlding
I'm looking at deploying "POPs" at several IDCs across the globe.
Each POP will contain several servers. (At most ten.) I would like each POP
to use the same set of IP addresses; connections to these IP addresses will
get to the nearest POP by virtue of routing.
[...]
Are there providers of such?
There are some ISPs and colo facilitators that work world wide. Having the
same ISP AND the same data center people in each location will probably
not be easy, though. And is there an important reason why you'd want to?
I would advise against choosing a single network, since that will at least
partially negate the advantages of "multihoming".
Will I be able to get a globally routable IP block for my AS?
For a hand full of hands full of servers? You could probably get a /24 or
a /23 at most. Those are not guaranteed to be globally routable. However,
you could request address space from the ISP at your main location, and
announce that address space at all locations. In places where this
announcement is filtered, you will still be reachable over your main ISPs
aggregate.
Or is my best bet to pick one provider which has global presence?
Large ISPs are less likely to peer with smaller networks at regional
exchange points. I would get a really large network as the main one and
use addresses from them, and medium sized networks that peer at several
regional exchange points for the other locations.
Iljitsch van Beijnum