Partial Use Of one Regions IP Block in another

George Bonser gbonser at
Thu May 20 16:14:36 UTC 2010

> -----Original Message-----
> From: Owen DeLong [mailto:owen at]
> Sent: Thursday, May 20, 2010 7:37 AM
> To: Net
> Cc: nanog at
> Subject: Re: Partial Use Of one Regions IP Block in another
> You state "Obv, the best approach...". I don't think so. I think the
> best
> approach is whatever allows you to make most efficient use of your
> address space. Usually this will be from a single RIR rather than a
> multiple RIR approach.
> Owen

The one drawback to that would be people who attempt to do geographical
based service provisioning. Say a company based in the US uses part of
their block in Europe or APAC.  When they do a DNS request for a service
address from $GLOBAL_CONTENT_PROVIDER, they end up getting the US
service address because the content provider believes the request is
coming from the US resulting in poor performance.  In other words, if a
service relies on connection to other services that try to do
geographical affinity, it could lead to a sub-optimal experience.

It could also cause problems where the content is different (or possibly
prohibited) depending on the geographical location of the requestor
which some folks try to determine by source address (but which is
actually quite idiotic, in my opinion, because as you see from this
thread, an IP address in no way relates to where the person really is,
it only relates to where the entity to whom it was issued is located).

Been there and experienced issues like that before.  It can even be bad
when you are given an IP block that might have been used before by
someone in another region.


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