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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

388.0. "Synoptic 3 MAC Concentrator" by VNASWS::HONISCH (Guenter Honisch ACT Austria) Tue Nov 12 1991 11:11

    Synoptic offers a 42 Port System 3000-05 Concentrator with Three MAC's.
    
    They say that this gives you 200 Mbps on the Dual Ring plus 100 Mbps on
    a internal Path.
    
    Another Advantage is the possibility to "move" a MAC through the
    Concentrator Ports to listen to a possible Problem.
    
    Also the Insertion of a new Station could be done on a isolated Ring,
    without disturbing the Primary Ring.
    
    Are all this Features covered in Standards , or are they "grey" Areas
    which Synoptic uses first ???
    
    Could somebody Knowledgable position our Solution to  Synoptics ??
    
    
    			Guenter

T.R Title User Personal
Name Date Lines

388.1 KONING::KONING Paul Koning, NI1D Tue Nov 12 1991 16:45 18

T.R	Title	User	Personal Name	Date	Lines
388.1		KONING::KONING	Paul Koning, NI1D	`Tue Nov 12 1991 16:45`	18
	You don't need multiple MACs to have data on both rings; you do that by having concentrators that can insert stations into either ring. Currently ours don't. Note that you lose the extra capacity when the ring wraps, so you get 100 Mb/s with fault tolerance or 200 Mb/s with NO fault tolerance. The "local" path, insertion without disturbing the ring, and all that stuff are all unspecified in the standard. Each of those mean a lot of extra complexity and cost in the concentrator for no significant benefit. For example, generally the performance of FDDI networks is limited by the host performance, not the network bandwidth. If network bandwidth IS an issue, it can be increased simply by setting up multiple parallel networks. That IS standard; the "local path" stuff is not. It is also more flexible, since you can get arbitrary performance, not just a factor of 2. I think there's a detailed discussion of "graceful insertion" earlier in this conference... paul

You don't need multiple MACs to have data on both rings; you do that by
having concentrators that can insert stations into either ring.  Currently
ours don't.  Note that you lose the extra capacity when the ring wraps,
so you get 100 Mb/s with fault tolerance or 200 Mb/s with NO fault tolerance.

The "local" path, insertion without disturbing the ring, and all that stuff
are all unspecified in the standard.  Each of those mean a lot of extra 
complexity and cost in the concentrator for no significant benefit.
For example, generally the performance of FDDI networks is limited by the
host performance, not the network bandwidth.  If network bandwidth IS an
issue, it can be increased simply by setting up multiple parallel networks.
That IS standard; the "local path" stuff is not.  It is also more flexible,
since you can get arbitrary performance, not just a factor of 2.

I think there's a detailed discussion of "graceful insertion" earlier in
this conference...

	paul