pst@dschub.dsc.com (Paul Tatarsky) (03/15/91)
Does anyone know of a fix for an incompatibility between MacTCP and a Cabletron E6000 NuBus Card. Here's a summary of the problem: MacIIcx, Cabletron E600 Card, MacTCP Drivers installed and properly configured. Applications: MacX and Intercon's TCP/Connect II-A (MacTCP version) Problem: the E6000 card seems to jam up whenever a large ammount of data starts being shipped back to the mac. (For example a ps -aex on a 60+ user machine) Tech Support: Intercon claims MacTCP and the E6000 don't work together. Said that Cabletron is working on it. Cabletron tech support has never heard of MacTCP but did offer a revision of the drivers numbered 2.1 (when I bought the card a month ago, it was on rev 1.09, which is a pretty big jump.) Any information you may have will be greatly appreciated. ------------------------------------------------------------------------ |\/\/\/| Paul Tatarsky | | Digital Sound Corp. `Makers of That VoiceMail Stuff` | | Internet: pst%dschub@hub.ucsb.edu | (o)(o) Uucp: pyramid!ucsbcsl!dschub!pst ( _) VMail: (805) 566-2255 x2234 | ,___| -- | / Matt Groenig Was Cooler When He Was Poor / \ Work is Hell -------------------------------------------------------------------------
resnick@cogsci.uiuc.edu (Pete Resnick) (03/15/91)
When an TCP connection hangs when sending large amounts of data using MacTCP on an Ethernet card, chances are it is one of those Ethernet cards that mishandles the maximum segment size (MSS). MSS is a number that MacTCP communicates to the remote host to tell it how big a piece of data can be sent. Some Ethernet cards (e.g. some Cabletron and Dove cards) are not communicating it correctly to MacTCP. There is a fix: In MacTCP 1.0, MacTCP did not figure out the MSS correctly for DDP-IP gateways, so Steve Dorner here at UIUC came up with a fix. This same fix still works on the newer versions of MacTCP and fixes the problem for Ethernet card. It seems to just tell MacTCP not to advertise any MSS to the remote host, which leaves it at a reasonable default. The fix is peformed with ResEdit as follows: 1. Open the MacTCP file with ResEdit. 2. Open the DRVR resources picker. 3. Open the one DRVR resource that is there. In older version of ResEdit, you must use the "Open General" choice. 4. Find the hexadecimal string "337c02040014" and change it to read "337c01010014". 5. Save and close the file. Now MacTCP should work properly. pr -- Pete Resnick (...so what is a mojo, and why would one be rising?) Graduate assistant - Philosophy Department, Gregory Hall, UIUC System manager - Cognitive Science Group, Beckman Institute, UIUC Internet/ARPAnet/EDUnet : resnick@cogsci.uiuc.edu BITNET (if no other way) : FREE0285@UIUCVMD
ziff@zip.eecs.umich.edu (Brian Moore) (03/16/91)
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! Brian Moore DCO Macintosh Consultant ziff@eecs.umich.edu Disclaimer: Blah, blah, blah, it's only speak for myself, blah, blah, blah, ...
dorner@pequod.cso.uiuc.edu (Steve Dorner) (03/17/91)
>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