Hi folks, I'm busily writing up my next lecture for my TCP/IP course at CUNY Hunter (text is Comer vol. 1 4th edition), the topic is the base Internet Protocol datagram format. I come to the TOS field which, as all know, was originally specified in the base IP specification RFC 791 then attempt to extend and reconcile it with later RFCs made in RFC 1349 followed subsequently in RFC 2474 in late 1998 which completely changed it to support DiffServ. In RFC 791 on page 11, Jon Postel writes: Several networks offer service precedence, which somehow treats high precedence traffic as more important than other traffic (generally by accepting only traffic above a certain precedence at time of high load). The major choice is a three way tradeoff between low-delay, high-reliability, and high-throughput. Was this something actually supported in the Internet? Widely? any examples of who? Around when did it stop being supported? Did anyone ever actually support RFC1349 in a host or router? How about DiffServ as specified in 2474 and 2475? I believe there are router implementations but is anyone actually got it turned on ? Possibly only in an IP "intranet"? Dana Hudes CSCI Dept CUNY Hunter College