[cisco-nas] OT - routing ARIN /22 blocks

[Jon Lewis]

On Fri, 23 Jul 2004, Adam Greene wrote:

> This is not exactly a cisco-nas issue, but I thought perhaps someone on this
> list might be able to help me out on this one, as I know there's lots of ISP
> folks listening....

This isn't even close to a cisco-nas issue.  cisco-nsp would have been
slightly more appropriate.  isp-bgp, or inet-access would have been the
'right' lists to post to.

> We are a multi-homed ISP and have just gotten approval from ARIN for a /22
> IP allocation. This is fabulous for us, as it means that finally after all

You must be a small and unusual ISP to be multihomed but only using enough
IP space to qualify for a /22.  What services do you provide?

> these years, we will stop being tied to our upstream provider(s) for IP
> space. However, before we break out the champagne and renumber for the nth
> time, I must pose the question: is this /22 going to be globally routable?

No.  Nothing is globally routable.  There's always some idiot somewhere
with unreasonable or outdated filters that will block your packets.  The
question is, is this space going to be routable enough for your customers
to either not notice or not care about those networks that won't see you?

What block of IP space did you get?  If it's from something in the low
70's/8, see http://69box.atlantic.net/ for a taste of what you may be in
for.  That site is also reachable as http://not69box.atlantic.net/ for the
filter challenged.

> According to RFC 2050, "addresses issued directly from the IRs (non-provider
> based), are the least likely to be routable across the Internet."

Likely because they're newer, smaller blocks, so you're much more likely
to run into networks with outdated bogon filters, networks that filter
prefixes longer than a certain size, etc.

If you haven't already done so, get your ASN and IP space setup in one of
the routing registries.  ARIN and altdb are two free choices.  Others may
want to charge you for the service.  Some providers build their BGP
filters based on info from the routing registries.

Then, before you renumber, start announcing the new space and route some
of it to a PC and see that you can reach some of the higher profile sites
on the net.

----------------------------------------------------------------------
 Jon Lewis                   |  I route
 Senior Network Engineer     |  therefore you are
 Atlantic Net                |
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