[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

818.0. "Roving/Moving MAC" by GRANMA::RHARPER () Mon Dec 21 1992 23:35

    Has anyone heard of roving or moving MAC?  I am told it is a new
    modification to a MIB, in which the FDDI device is tested prior to
    being added to the ring.  Any help is appreciated.
T.RTitleUserPersonal
Name
DateLines
818.1KONING::KONINGPaul Koning, A-13683Tue Dec 22 1992 10:277
"Roving MAC" is a codeword for a complex non-standard feature that some
concentrator makers have added to their product, and attempt to sell as 
something useful.  There are lots of excuses for it, none technically
sound.  For example, "testing" is something all FDDI devices do already
(using Link Confidence Test).

	paul
818.2anymore data?GRANMA::RHARPERMon Jan 04 1993 11:554
    Do you know where I could get more info on it?  I'd like to be able to
    discuss it usefullness with my customer.
    
    Rich
818.3In DEC products?JUMP4::JOYHappy at lastMon Jan 04 1993 13:0912
    I just saw a message from Bruce Sweet which says that the FDDI
    Concentrator in the DEChub 900 with have a "Roving" MAC. I was shocked
    to read this after all the bashing we've done around this topic for the
    past several years. Is there really a good reason to have this in our
    concentrator or are we just knuckling under to pressure from customers
    who don't understand how it works?
    
    First DAS PC adapters, now roving MACs.......we certainly have changed
    our tune on a lot of issues lately.
    
    Debbie
    
818.4No Roving MACQUIVER::PARISEAULuc PariseauTue Jan 05 1993 08:3015
	In the HUB we will be able to place all PHYs and the MAC on the
	Primary OR Secondary Path.  There will be no Local Path.
	It is an all or nothing deal.  ALL Ports + MAC are always on the
	same path together.

	I guess it depends how you define Roving MAC, but I don't think
	this is what people would expect.  Our MAC will not be able to
	move to a single port for 'testing' (as Paul mentioned).

	rove : to wander about at random

	I sure hope our MAC doesn't 'wander about at random'.

	Luc 
818.5Thanks for clarificationJUMP4::JOYHappy at lastTue Jan 05 1993 09:297
    Luc,
       Thanks for the clarification. Our MAC sounds a bit more rational
    than other vendors who use the term "roving". They seem to stick more
    closely to the dictionary definition you gave.
    
    Debbie
    
818.6KONING::KONINGPaul Koning, A-13683Tue Jan 05 1993 10:094
What was talked about is a dual path concentrator; that's quite another beast.
Such things are fully defined by the standard and have meaningful properties.

	paul
818.7What is a Dual Path Concentrator?DPDMAI::DAVIESMark, SCA Area Network ConsultantTue Jan 05 1993 15:207
    OK.  The DEChub 900 FDDI concentrator is a "dual path concentrator".
    
    How is one of these different from a standard concentartor such as the
    DC500?
    
    Mark
    
818.8Empty secondary on DC500QUIVER::PARISEAULuc PariseauWed Jan 06 1993 09:0017
	The old concentrator had a secondary path but the M ports and
	MAC could only go on the primary path.  The HUB concentrator
	can place the M ports and MAC all on the primary PATH OR all on the
	secondary PATH (be carefull..."primary ring" doesn't always mean
	the same as "primary path"...I can explain that some other time).

	For those that don't know why you would want to do this, the
	idea is that now you can use the secondary ring AND the primary
	ring simultaneously and get 200 Mbps IF your trunk ring is NOT
	wrapped (which is normally true).  Which also means you need a
	bridge/router between your primary and secondary rings (like two
	ports of a GIGAswitch...or just get a 22 port GIGAswitch to start
	with and get 22 "rings"...22 X 100 = 2200 Mbps and a lot less
	confusion!)

	Luc
818.9path vs ring?DPDMAI::DAVIESMark, SCA Area Network ConsultantWed Jan 06 1993 09:1911
    I am still confused.  You say that either ALL the MACs/ports can placed
    on the primary or secondary path, but not a few on each.  This doesn't
    seem to take advantage of the "200Mbps available" on both rings if all
    MACs are on the same ring.
    
    Maybe I need to understand better the relation of a path and a ring.
    
    Regards,
    
    Mark
    
818.10Perception = RealityJUMP4::JOYHappy at lastWed Jan 06 1993 12:3716
    Mark,
       I'm taking a guess here, but I think the idea is that you would run
    one set of fiber pairs to create your dual-ring, then you could place
    multiple concentrators on either the primary or the seconardy "path"
    with a bridge or router between them to create a simulated 200 Mbps
    FDDI network. If you used a bridge, the fact that the systems connected
    to the concentrators were on two seperate paths would be invisible
    (given a full speed 100-100 bridge) so you could build something like a
    cluster, with half the nodes on one path and half on the other and you
    can give the impression of having 200 Mbps between nodes. 
    
    Maybe we're finally getting the hang of "marketing" our features like
    SYnoptics and Cisco do....perception is reality, right?
    
    Deb