On 2013/04/17 12:14, Alasdair Lumsden wrote: > On 17/04/2013 12:07, Ricky Blaikie wrote: > >>what's considered to be the smallest v4 block which would be globally > >>routable given BGP prefix filtering? > > > > > >/24 isn't it? > > We announce a /24 of PI space on behalf of one of our clients and > periodically (although not frequently) they find places they can't > reach due to aggressive prefix filtering. But on the whole it seems > completely usable. > > I would expect a /25 to be a very different story though. >
/24 from a block that was originally used for /24's (swamp or LIR PI assignments) seems to be fairly OK, but I have heard of people having bigger problems when they try and route a /24 carved from a larger PA block routed separately from that block. (Yes it is meant to be aggregated, but there is no other source of address space for small networks who want to start multi homing in the RIPE region now, so I think we can expect to see use of this increasing).
