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Conference netcad::hub_mgnt

Title:DEChub/HUBwatch/PROBEwatch CONFERENCE
Notice:Firmware -2, Doc -3, Power -4, HW kits -5, firm load -6&7
Moderator:NETCAD::COLELLADT
Created:Wed Nov 13 1991
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:4455
Total number of notes:16761

280.0. "DECbridge 90/CHIPcomm Ethermodem Compatibility problem" by CX3PST::HTKING::M_SHELDON () Tue Jun 22 1993 17:50

I was just contacted by a customer asking about a fix for the DECbridge 90.
He was with QUAKER OATS and got information that there was a recently
discovered compatibility problem between DECbridge 90's and CHIPcomm
EtherWorks Modems #3 and #4. He indicated that the problem involved
collisions and extra preamble bits sent out by the DECbridge 90 and that
Digital was supposed to be aware of it. 

Does anyone have any idea what he is talking about ?

If so, can you give me more information about a fix ?

Thanks for any assistance.

							Mike Sheldon 		
							Colorado CSC
T.RTitleUserPersonal
Name
DateLines
280.1Use long cablesPRNSYS::LOMICKAJJeffrey A. LomickaTue Jul 06 1993 13:2110
Recent is only "recent" if recent includes everything in the last two
years.

This is a known interoperability problem, although we aren't sure WHY
the Ethermodems choke on the AUI signals.  This is the first I heard
that it had anything to do with preamble bits.  The off-the-shelf
solution is to use longer AUI cables, as this usually fixes it.  It was
investigated at some length by SASE, but they haven't yet implemented a
fix for it.

280.2CX3PST::HTKING::M_SHELDONTue Jul 06 1993 15:017
Thanks...

The customer says that the person at Chipcomm backed off somewhat on
his claim that DEC was at fault. Customer is investigating further.


							Mike Sheldon
280.3Solved at XeroxFPTVX1::WELLSRick Wells, @FPT/DTN 384-5112Tue Jul 13 1993 15:485
    We had the same problem at Xerox Corp. here in Webster, NY.  Solved the
    problem with 20 meter tranceiver cables between the Chipcoms and the
    DECbridge 90s.  A little ridiculous since we had a box of BNE4D-02s. 
    But it worked!  Larry Morse at CSC gave me additional information. 
    (CSC32::L_MORSE).
280.4Longer cables did not helpCX3PST::HTKING::M_SHELDONTue Jul 13 1993 18:133
We had to CLD this problem.... Longer cables did not help.....

							Mike Sheldon