Hi Jerry, Based on our discussion yesterday I will try and summarize the current thinking on STPs: STP is a tuple which is formed as: Network_Id:Local_id where: Network_id is an string (unformatted - no syntax specified) which identifies a group of resources available to a single service. Each Network has an associated NSA, i.e. there is a 1:1 relationship between and NSA instance and a Network. A single stage lookup is required to find the address of the NSA from the Network_id. Local_id is a string (unformatted - no syntax specified) which identifies a local resource (or endpoint). A federating NSA has the option (not compulsory) of swapping the Network and Local parts of the STP. Both parts must be swapped (not just the network part) this removes the need for Local_id to be globally unique. (this is like MLPS label swapping) Does this align with your view? Guy _____________________________________________________________________ ** Guy Roberts, PhD Network Engineering & Planning * * Tel: +44 (0)1223 371300 * * City House Direct: +44 (0)1223 371316 * 126-130 Hills Road Fax: +44 (0)1223 371371 * Cambridge * CB2 1PQ E-mail: guy.roberts@dante.net<mailto:guy.roberts@dante.org.uk> D A N T E United Kingdom WWW: http://www.dante.net _____________________________________________________________________