Perhaps transit networks should receive 16-bit ASNs. Leaf networks would use { a special ASN | I'm still brainstorming | who knows } and carry an "available upstreams" BGP tag for each upstream. Metrics are calculated for each transit AS. Those metrics are then combined with <as yet unspecified intelligence in "available upstreams" tag> for each leaf ASN. BGP loop detection might present a problem if all leaf ASNs use, say, 16-bit AS65535. If existing allowas-in is too coarse, refer to "32-bit ASN" BGP attribute for fine-grained control. In short: I'm trying to think up a mechanism that performs full Dijkstra calculations _only_ for transit networks, and uses some cheaper version for the degenerate case of a leaf network. Eddy -- Everquick Internet - http://www.everquick.net/ A division of Brotsman & Dreger, Inc. - http://www.brotsman.com/ Bandwidth, consulting, e-commerce, hosting, and network building Phone: +1 785 865 5885 Lawrence and [inter]national Phone: +1 316 794 8922 Wichita ________________________________________________________________________ DO NOT send mail to the following addresses: davidc@brics.com -*- jfconmaapaq@intc.net -*- sam@everquick.net Sending mail to spambait addresses is a great way to get blocked.