anthony@NMS.HLS.COM (Anthony Chung) (01/19/91)
In Telnet Specs, DATA MARK should be sent with TCP URGENT flag set. I found SUN's implementation does not send TCP URGENT with TELNET DATA MARK all the times. Is it required to send DATA MARK with TCP Urgent?
braden@VENERA.ISI.EDU (01/22/91)
From tcp-ip-RELAY@NIC.DDN.MIL Sun Jan 20 10:49:59 1991 From: anthony@nms.hls.com (Anthony Chung) Subject: TCP Urgent flag with TELNET DATA MARK To: tcp-ip@nic.ddn.mil Date: Fri, 18 Jan 91 16:12:40 PDT X-Mailer: ELM [version 2.2 PL0] In Telnet Specs, DATA MARK should be sent with TCP URGENT flag set. I found SUN's implementation does not send TCP URGENT with TELNET DATA MARK all the times. Is it required to send DATA MARK with TCP Urgent? Anthony, The original Telnet spec (RFC-874 is pretty clear that it is required. In fact, use of the Data Mark is defined only when sent with as TCP urgent data. The Data Mark is defined as "The data stream portion of a Synch" (RFC-874 p14), and "A Synch signal consists of a TCP Urgent notification, coupled with the TELNET command DATA MARK" (ibid, p. 9). The Host Requirements RFC-1123, section 3.2.4, is intended to reinforce this requirement. Bob Braden