Newsgroups: comp.sys.mac.comm
Path: utzoo!utgpu!cunews!bnrgate!bwdls61.bnr.ca!bnr.ca!bschmidt
From: bschmidt@bnr.ca (Ben Schmidt)
Subject: Re: MacTCP problem
Message-ID: <1990Dec3.130757.4405@bwdls61.bnr.ca>
References:<1990Nov30.205337.8345@ux1.cso.uiuc.edu> <693@nih-csl.nih.gov> <BRAD.90Dec1133259@andros.cayman.com>
Sender: usenet@bwdls61.bnr.ca (Use Net)
Organization: Bell-Northern Research
Date: Mon, 3 Dec 90 13:07:57 GMT

In article <BRAD.90Dec1133259@andros.cayman.com> brad@andros.cayman.com 
(Brad Parker) writes:
>> In article <693@nih-csl.nih.gov> ken@helix.nih.gov (Ken Weeks) writes:
>> 
>>    I've been using NCSA Telnet to talk to my VAX, which is running a
>>    Telnet server.  I recently "converted" from the embedded TCP driver 
>>    version to the Mac TCP version. No problems at first...but as of late, 
>>    I've noticed a severe, repeatable "hang" when I use the VMS "TYPE"
>>    commands, or list a long directory. Just that session hangs - I can log
>>    in again and kill it 

> I think the "mss" or maximum segment size of the TCP you are using is
> too large for your gateway.  Under NCSA you can set it (in the
> config.tel file) to a small number like 512 which will not require
> that you gateway fragment the packets. Under MacTCP, is it not settable, 
> and I think MacTCP 1.0 has a bug which causes it to guess wrong; (or at 
> least guess a number which causes you to need a gateway which will fragment
> properly)
> 
> I'll go out on a limb and guess that your mac is on localtalk and you're
> using a gateway to get to the ethernet. If the gateway is a fastpath, it
> may not support fragmentation of IP packets too big to be encapsulated
> in a single localtalk packet (~600 bytes); If the gateway is a gatorbox,
> you're software may be out of date as we used to have this problem
> but fixed it.

Yup.  It sure sounds like a MacTCP 1.0 bug with MSS which affected Macs on 
LocalTalk.   Are you using MacTCP 1.01?

Ben Schmidt     Bell-Northern Research, Ltd.   Ph: (613) 763-3906
Information     P.O. Box 3511, Station C       FAX:(613) 763-3283
Technology      Ottawa Canada K1Y 4H7          bschmidt@bnr.ca
