Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!ucsd!ucbvax!ain.ESD.3Com.COM!rxk From: rxk@ain.ESD.3Com.COM (Rajeev Kochhar) Newsgroups: comp.protocols.tcp-ip Subject: Re: Problem with Xmodem and 3Com terminal server Message-ID: <9011071849.AA21432@ain.ESD.3Com.COM> Date: 7 Nov 90 18:49:14 GMT Sender: daemon@ucbvax.BERKELEY.EDU Organization: The Internet Lines: 67 mmorse@Z.NSF.GOV ("Michael H. Morse") writes: >I am having a problem getting Xmodem to work between a Sun workstation >and a PC running a terminal emulator. >The PC uses a modem and a dial-up line to communicate, but it cannot >get to the workstation directly because the workstation has no serial >ports. Instead, the PC logs on to some other host, and then uses >telnet to get to the workstation. >We have a 3Com terminal server that is normally used in this situation, >but we've found that Xmodem does not work (the PC nacks everything it >gets) in this configuration. However, if the PC logs onto one of our >Ultrix hosts, and in effect uses it for a terminal server to telnet to >the workstation, Xmodem works fine. Subsequent tests have absolved the >terminal emulator (on the PC) and the xmodem program on the >workstation, leaving suspicion around the telnet implementation >on the terminal server. >I suspect this has something to do with parity, since the ASCII >characters transmitted by Xmodem, and received by the PC are >identical. Has anybody run into a similar problem? Any information on >how telnet reacts when raw mode is selected would be appreciated. >Thanks in advance. >--Mike >-- >Michael Morse Internet: mmorse@note.nsf.gov >National Science Foundation BITNET: mmorse@NSF > Telephone: (202) 357-7659 > FAX: (202) 357-7663 The dicussion following the above posting raised a few points about the 3Com terminal server which I want to clarify. The server does support 8-bit (binary transmission) mode in Telnet. The server can initiate negotiation for 8-bit transmission any time during a session. When the server initiates a connection it negotiates 8-bit mode based on the setting of the XmitBinary (can be ON or OFF) parameter. Default value is off. When the terminal server is the server side of a connection it negotiates 8-bit mode by default. The server has a parameter called NetAscii which determines the character sequence transmitted when a is seen at the terminal port. Can be configured to transmit or . However, in 8-bit mode, no extra characters are added to the data stream (i.e. NetAscii is ignored). For a completely transparent session the terminal parameters should be set as following: XmitBinary = ON FlowControlTo = none FlowControlFrom = none ECMChar = disable BreakChar = disable DataBits = 8 Parity = None Hope this helps, -Rajeev Kochhar 3Com Disclaimer: Comments reflect my own understanding and opinion.