Please note that the network layer QOS (e.g., RSVP, DiffServe, and/or MPLS) may or may not have the end-to-end significance. For example, an IP network may implement different QOS schemes in different domains (e.g., RVSP in one domain, DiffServ in another domain). However, the application layer QOS is end-to-end that remains the same. For example, an H.323 or SIP call that can traverse several IP domains where each domain may implement its own network layer QOS schemes while the H.323/SIP call carry the signaling messages and QOS parameters end-to-end independent of the underlying network layer QOS mechanisms. Yes, the application layer is end-to-end. But does it traverse the exact same route as RTP transport layer? I don't think so, in that this is not IP. IP routes each packet individually with the right to change routes independently for each stream, and each packet in a stream. This is the basis for load balancing, overload control, and link failure survivability. With this in mind, the application layer can negotiate an end-to-end QOS with the ends. It cannot control the intermediate routing nodes. A method is needed to accomplish the end-to-end QOS control via the RTP IP stream. Bob -------------------------------------------------------------- Robert Callaghan Siemens Enterprise Networks 5500 Broken Sound Blvd, Boca Raton, Fl 33487 Tel: +1 561 923-1756 Fax: +1 561 923-1403 Email: Robert.Callaghan@ICN.Siemens.com ----------------------------------------------------------------- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ For help on this mail list, send "HELP ITU-SG16" in a message to listserv@mailbag.intel.com