Hi, I do appreciate real life is often more complex than high flying ideals. But aggregation and general good practice would mean in an ideal world you would invest in the internal infrastructure to connect your data centres together with a network and run an IGP+iBGP plus advertise the /21 eBGP at both sites to upstreams. It could be argued that the cost of building the network to run your AS is part and parcel of the expense of opening new datacenter - rather than this ever increasing route table growth. Plus if you de-aggregate as intended you can not announce a covering route for the /21 due to no internal connectivity and if this puts the /22 under the minimum allocation size for the RIR block your IP space comes from then don't be surprised when it gets filtered out and people end up having to accept no routing to your network at all or, sum optimal via a default. But life is rarely as simple as ideals. My 2e Ben -----Original Message----- From: Scott Morris [mailto:swm@emanon.com] Sent: 22 May 2008 17:49 To: 'James Kelty'; nanog@nanog.org Subject: RE: Splitting ARIN assignment As long as your upstreams/partners are cool with that, there is no related designation between how addresses are allocated versus how they are announced. In other words, TECHNICALLY you could advertise a whole bunch of /30's.... You just run the risk of being filtered and/or ridiculed along the way. :) But splitting the /22's from the same announcing AS shouldn't cause any problems as long as you design your connectivity ok. Scott -----Original Message----- From: James Kelty [mailto:jkelty@pandora.com] Sent: Thursday, May 22, 2008 12:39 PM To: nanog@nanog.org Subject: Splitting ARIN assignment Hey all, I'm looking for an opinion from the group. I have an ARIN /21 assignment and a new requirement for a second data center. Rather than ask for another assignment, I would like to advertise one /22 from one location and the other /22 from the second location both with the same asn. My apps will work that way, so I don't have an issue internally, but I'm looking for a broader base opinion on that. Thanks a lot! -James