[Search for users] [Overall Top Noters] [List of all Conferences] [Download this site]

Conference 7.286::fddi

Title:	FDDI - The Next Generation

Moderator:	NETCAD::STEFANI

Created:	Thu Apr 27 1989
Last Modified:	Thu Jun 05 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	2259
Total number of notes:	8590

636.0. "DEMFA" by UTRTSC::GUEDHA () Wed Jul 08 1992 04:02

     
Hello All,

can anyone explain 

From:

VMS Version 5.5 New Features
Manual page A50

A.3.3.2 New FDDI device DEMFA

The DEMFA and FXDRIVER can support only one multicast user at a time. Also,
the maximum number of channels that can be assigned to single DEMFA device 
is 29 (DECnet, LAT, and clusters each count as one channel).

	a) Should I understand (only one multicast user at the time)
	   only one protocol DECnet or LAT is allowed to run ?
	b) single DEMFA device maximum of 29 channels, is that means DEMFA
	   will run 29 different protocols at the same time ?

regards 	 
		.Moha

T.R	Title	User	Personal Name	Date	Lines
636.1	DEMFA answers	STAR::GAGNE	David Gagne - VMS/LAN Development	`Wed Jul 08 1992 08:14`	8
	a) The DEMFA will only support one ALL MULTICAST user (MLT parameter in the VMS QIO STARTUP). All 29 channels can be "normal" users that just enable specific multicast addresses. An ALL MULTICAST user enables all multicast addresses for their protocol. The DEMFA can only support one such (ALL MULTICAST) user. The second channel that tries to start as with ALL MULTICAST enabled, will get the error SS$_DEVREQERR. b) Yes, the 29 channels represent 29 protocols.
636.2	Clarification of ALL MULTICAST USER	MSBCS::REGE		`Wed Jul 08 1992 12:11`	13
	Ref. -.1 Note ALL MULTICAST USER is a special user that gets a packet with multicast destination address that is not enabled by any other user. Individual users (all 29 of them, if there is a need) can specify multicast addresses. Only limit is that the sum of all different physical and multicast addresses cannot be more than 63. /satish
636.3		KONING::KONING	Paul Koning, A-13683	`Wed Jul 08 1992 13:31`	4
	Wow, that's a very nasty typo. Is the typo in .0, or in the document being quoted? (If the latter, this is worth fixing FAST!) paul
636.4	Another form of ALL MULTICAST	STAR::GAGNE	David Gagne - VMS/LAN Development	`Wed Jul 08 1992 20:39`	4
	Another form of ALL MULTICAST user is a user that enables more than 6 multicast addresses. This is the VMS driver making the decision that once a user enabled more than 6 multicast, it will just enable ALL MULTICAST on the device (for that user).
636.5		KONING::KONING	Paul Koning, A-13683	`Thu Jul 09 1992 13:37`	6
	Does this mean that it is not possible for two users to enable 8 multicast addresses apiece? I hope not... it's reasonable to have a restriction on the explicit use of a special mode such as "all multicast", but not in the case where a user simply asks for a couple of multicast addresses explicitly. paul
636.6	yes, but no problems	STAR::GAGNE	David Gagne - VMS/LAN Development	`Mon Jul 13 1992 15:42`	4
	Yes, two users cannot enable 8 multicasts each. Sorry, but that is the current VMS implementation of enabling multicast addresses. We have had no complaints to date - probably because there is only one protocol that enables more than 6 multicast addresses.