BGP Homing Question

Fri Aug 27 12:58:53 UTC 2004

On 27 Aug 2004, at 08:13, Rick Lowery wrote:

> If someone owns their own /20 which they received from Arin back in 
> the day and they want to subnet and use part of it (/24) in Europe. 
> Would their be any problems if the wanted to advertise the North 
> American issued space from a European AS?

There should be no technical problem due to the origins of the numbers.

There might be a problem with some operators filtering out the /24 if 
it's allocated from a block with consistent /20 allocation boundaries. 
However, if it's an old allocation this is not necessarily going to be 
the case (and many people are not that enthusiastic about allocation 
boundary filtering anyway).

If you poke around on www.arin.net you should find summaries by /8 for 
the longest allocation within each block. The paragraph above is only a 
concern if your specific /20 lives in a /8 where the longest allocation 
made by ARIN has a mask length less than 24 bits.

> I know they would not be good Internet citizen, but if they needed to 
> do this for a temp basis does anyone see an issue?

There's not much bad citizenry in what you are suggesting: the 
assigning-RIR problem is a non-problem, and your two sites are still 
only going to originate one prefix each (which they would presumably do 
even if you had a separate LIR assignment for the European node).

Joe