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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

942.0. "Polarity detect on UTP PMD?" by WOTVAX::PARRIS () Thu Apr 28 1994 12:04

I've been asked if the UTP PMD for the DECconcentrator 900MX detects 
wrong polarity and reverses it like the DECrepeater 900TM?

Another question which I must admit I don't understand is - do the 
DECconcentrator 900MX and the DECrepeater have a hard cache table?

Any help will be very welcome.

T.R	Title	User	Date	Lines
942.1		QUIVER::SLAWRENCE	`Fri Apr 29 1994 13:03`	6
	I'll try to find out about the PMD. I don't understand the second question either - get whoever asked to explain the question (and then ask them what the problem is that they think it will solve).
942.2	no polarity fix	QUIVER::SLAWRENCE	`Fri Apr 29 1994 18:16`	3
	The UTP PMD for DECconcentrator900MX does not correct for wrong polarity.
942.3	There is no polarity to worry about	LEVERS::B_CRONIN	`Wed Aug 17 1994 10:07`	9
	I just saw this - maybe this will help. The TP-PMD uses a code called MLT-3, in which the transitions encode the data. It is the transition itself, not the polarity of the transition that carries the data. Because of this, there is no polarity like there is with 10base-t, hence, no need to worry about it being reversed. Bill