BGP AS question

Cliff Bowles cliff.bowles at
Thu Oct 27 18:51:55 UTC 2011

Greetings. We have a few facilities within a 30 mile radius, and each has an ISP link. We use P2P links at the edge to make certain traffic sourcing from one facility, and destined to the Public IPs at another, stay on the "dirty" links rather than punting out to the ISP. All sites use the same BGP AS.

Recently, we were required to turn up an additional facility in a short time frame. It also uses the same BGP AS. However, it does not have a dirty cross-connect link. So, even though this facility has unique /24 public IP blocks, it still has the same AS.

One thing we are noticing is that some ISPs don't seem to have a problem allowing this traffic, and some do. I suspect some don't like traffic with the same source and destination BGP AS, even though the prefixes are different at each location. But other ISPs seem to permit this with no problem.

My question is: is normal BGP default behavior to permit or to allow this type of traffic? Also, would it be easier to ask the ISP to make an exception, or to buy another AS for the rogue facility?


Clifford W Bowles, Technical Director
Apollo Group | IT Services | Network Engineering
4025 S. Riverpoint Parkway | CF-C201 | Phoenix, AZ  85040
phone: 602-557-6762 | fax: 602-557-6607 | email: cliff.bowles at<mailto:cliff.bowles at>

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