BGP, splitting an AS

[christopher.bunting]

Hello,

I have a quick query that I'm hoping someone can help me with.

I have a /20 block of public IP addresses, currently located in a data centre in Amsterdam. I am now setting up a new hosting centre in New York, and I want to move a /21 portion of this address space to the new site. The sites will be completely separate, no connection between the 2. I'm looking to have something like the following (private addresses and example AS number used):

10.10.0.0/21, AS 1, routed through Amsterdam ISP

10.10.8.0/21, AS 1, routed through New Yowk ISP

I don't see any initial problems with BGP's loop prevention due to AS paths, etc, but can anyone offer any further insight? Is it possible to simple advertise the /21 in each location?

Many thanks in advance.

[Konstantin Dunaev]

I'd say  you can't or better to say -  may not  use the adress from RIPE in the other region, ARIN in your case.

I mean technicaly it could be possible, but I think all top level ISP's will filter such a prefixes as they violate the IANA "IP Policy"

[christopher.bunting]

RIPE have actually told me that's it's fine, and it's possible to split the AS so long as it is hosted in 2 different regions. I'm awaiting ARIN's response to the same query.

At this time I just want to know if it's technically possible from the BGP perspective.

Thanks,

Chris

[Konstantin Dunaev]

from BGP point of view  - yes. But I don't think it's possible in practice.

All ISP in RIPE region use RIPE database information, especially the "route" object, in order to filter the prefix announcements from the clients, if there is no "route" object for a prefix - that prefix will be not be accepted.

I suppose the same procedure exists in ARIN region too (may be they use different names) , but you can't create "route" object in ARIN database for the prefix which allocated in RIPE database.

Ask you provider in USA if they can accept the prefix which is allocated by RIPE.

[christopher.bunting]

OK thanks, that does make sense. For clarity sake, this is one of the repsonses I received from RIPE:

"RIPE NCC allows duplicating AS Numbers from outside of the RIPE NCC service region into the RIPE Database, to be referenced in a RIPE sourced route object."

This, however, does not account for the prefix filtering issues at the ARIN region ISPs that you mention above. It seems strange that RIPE would not mention this, unless I or they have misunderstood something.

I'll see what ARIN come back to me with, they seem a little slow to respond in comparison!

Thanks again,

Chris

[Konstantin Dunaev]

I think  RIPE has really misunderstood what you asked for, they gave the answer only about AS number, and AS numbers can be really  used anywhere in world, but the use of IP address  is region "limited".

I'd suggest to ask RIPE again and clarify that you would like to use the RIPE-allocated IP address in USA.

[christopher.bunting]

Ok great, thanks again. I have asked RIPE for clarification on the matter and will let you know what they come back with.

[christopher.bunting]

Just FYI, I explained more clearly to RIPE what I would like to acheive and they still maintain it is possible. Most of the conversation was on the phone, but here's the email reply:

We can confirm you that it is possible to create a route object in the RIPE Database even if the prefix is allocated outside the RIPE region, for example in the ARIN region.

We suppose this is also possible on the other way around.

Still awaiting ARIN's response.

[Konstantin Dunaev · Accepted solution]

cool, it could be that they changed a policy, I always had a opinion that RIR's are not allow the use of their IP-Blocks in foreign regions.

You should clear it with a ISP in NY as well.

[christopher.bunting]

I shall do, and will report back if there's anything useful I think you would like to know.

Thanks for all the replies.

[Konstantin Dunaev]

Thank you, I'd be really interested.

I appreciate it!

[christopher.bunting]

ARIN have confirmed that do not allow any RIPE allocated resources to reside in the ARIN service region. Looks like I'll be filling out a rather lengthy address space request form!

[Konstantin Dunaev]

sorry to hear it, but it would be then too nice and easy .