CURRENT_MEETING_REPORT_ Reported by Jim Barnes/Xylogics Minutes of the TCP Multiplexing BOF (TMUX) Agenda o Introduction o How we got here o TMux Overview and implementation experience o Issues from the mailing list o What now Peter Cameron presented a short overview of the TMux protocol and gave a summary of the implementation experiences to date. TMux has been implemented in Unix System V.4 streams and BSD 4.3 systems. The total number of implementations to date is six. Peter noted that since the interface between the IP and TCP layers is not well defined, implementing a portable TMux module can be difficult. A problem with FTP traffic was also noted when there was a single FTP session. The implementations of TMux now do not attempt to multiplex FTP traffic. Only Telnet and Rlogin data is multiplexed now. The results from some performance tests simulating multiple Telnet sessions were reviewed. The following discussion resulted in requests for additional performance information including perceived response times for TMux versus non-TMux situations. Peter took the action item to send additional performance numbers to the mailing list. After the presentation, a general discussion followed. The following significant points were raised: o Since we want to prevent intermediate nodes from fragmenting and reconstructing TMux frames, the ``do not fragment'' flag should be set. o The document needs to include an applicability statement. o If the TMux implementation begins to see timeouts with exactly one datagram in the packet (that is, there is little traffic to multiplex), TMux should be turned off. o A packet with the IP OPTIONS field is not a candidate for multiplexing with TMux. o Check the test implementations to make sure everything that was done to overcome an implementation problem is reflected in the draft document. Discussion then moved on to consider specific points raised on the mailing list. o Length field: The consensus is that the length field should be 16 bits. o Checksums: After considerable discussion, no real consensus was reached, so the checksum field will stay in. A lengthy message from Don Eastlake was posted to the mailing list just before the BOF. The issues raised and the consensus reached during the BOF were as follows: o The document is too terminal server centric. The consensus of the BOF attendees was that TMux was a simple solution for a very specific problem. The problem definition should remain tightly focussed. o Type of Service concerns. TMux should ensure that all datagrams within the multiplexed packet have the same TOS. o Broadcast packets. Only unicast addresses should be allowed. o Larger limit on the maximum size of TMux datagrams. The maximum size of 30 will be replaced with information gained during implementation. This max datagram size probably should be configurable. o Use TMux only in congested situations. Agreed. o The section on security needs clarification. Agreed. The attendees were asked if there were any blocking issues that would prevent TMux from being put on the standards track. No one raised any such issue and the consensus was that TMux could be recommended to the IESG for further action. Attendees Steve Alexander stevea@lachman.com Jim Barnes barnes@xylogics.com David Borman dab@cray.com Peter Cameron cameron@xylint.co.uk Lida Carrier lida@apple.com Alan Clegg abc@concert.net David Crocker dcrocker@mordor.stanford.edu Chuck de Sostoa chuckd@cup.hp.com Marc Hasson marc@mentat.com Jeff Hilgeman jeffh@apertus.com William Kwan kwan@rabbit.com David Lapp lapp@waterloo.hp.com Walter Lazear lazear@gateway.mitre.org Allison Mankin mankin@cmf.nrl.navy.mil Matt Mathis mathis@psc.edu Marjo Mercado marjo@cup.hp.com William Palter palter@tgv.com Kanan Shah kshah@cmf.nrl.navy.mil Kitty Shih kmshih@novell.com Hoe Trinh htrinh@vnet.ibm.com John Vollbrecht jrv@merit.edu Walter Wimer walter.wimer@andrew.cmu.edu Weiping Zhao zhao@nacsis.ac.jp