Path: utzoo!news-server.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!zaphod.mps.ohio-state.edu!sdd.hp.com!spool.mu.edu!uwm.edu!ux1.cso.uiuc.edu!pequod.cso.uiuc.edu!dorner From: dorner@pequod.cso.uiuc.edu (Steve Dorner) Newsgroups: comp.sys.mac.comm Subject: Re: MacTCP and Cabletron E6000 Keywords: mac,ethernet,tcp Message-ID: <1991Mar16.161451.29664@ux1.cso.uiuc.edu> Date: 16 Mar 91 16:14:51 GMT References: <1991Mar15.204057.16093@zip.eecs.umich.edu> Sender: usenet@ux1.cso.uiuc.edu (News) Distribution: usa Organization: University of Illinois at U-C Lines: 34 >I'm having the same problem with the NuBus Card and MacTCP. When I run >NCSA Telnet I can't FTP a file greater than 1024 bytes. If I do, the >session will hang and the file will be zero bytes. But this is the strange >part, if I use HyperFTP I can FTP any size file I want. Figure that one out! If indeed the problem is MSS related, I can give you a possible explanation. Oversimplifications follow. The MSS (Maximum Segment Size) is the largest packet that can be send on the networks between point a and point b. If this is malnegotiated, you may wind up with packets too large to be transmitted on your network (bad). However, there is also the issue of TCP window size, which is the max amt of data that a host is willing to receive. The MacTCP xcmds may keep the window size down so low that the MSS is not an issue. That would be horribly inefficient, but might be convenient for HyperCard anyway. For those of you with glazed eyes, think of it another way. Imagine you and a friend each have a pool, and you want to fill yours from his. Further imagine you have a 2 gallon bucket (that's your MSS). Now, suppose the two of you decide that it 'looks' like a 5 gallon bucket (bug). If you say "Give me 5 gallons of water now" (window size), and he pours 5 gallons in the bucket, your shoes are wet (mind, since you both think the bucket holds 5 gallons, it's not an unreasonable request). If, on the other hand, you say "Give me a cup of water", your delusion about the size of the bucket isn't going to do any harm. (Of course, it's also going to take a while to fill your pool.) -- Steve Dorner, U of Illinois Computing Services Office Internet: s-dorner@uiuc.edu UUCP: uunet!uiucuxc!uiuc.edu!s-dorner