Conference 7.286::fddi

You should search this notes file for the info you are looking for. There is 
a lot of info regarding your subject.

See note 972, reply 1 for starters...

	paul

    re .1
    
    I don't feel like getting into a bit of name calling but before someone   
    makes a "suggestion" that there are lots of topics relating to void   
    frames in this conference, perhaps he/she should do a DIR/title=void (3   
    entries, 1251.2 was the only thing close) or show keyword/all (one   
    entry under void_frames (1251.2) and see how really few entries there   
    in fact are.
    
    If searching by title or keyword is an inappropriate way to search out
    information, too bad.  I DO NOT HAVE TIME TO READ EACH AND EVERY NOTE
    with titles like "WHY DO WE DO THESE THINGS".  Perhaps people who make
    entries here could spend a little more time to use descriptive titles.
    
    re .2
    
    Paul, thanks for the tip

>    If searching by title or keyword is an inappropriate way to search out
>    information, too bad.  I DO NOT HAVE TIME TO READ EACH AND EVERY NOTE
>    with titles like "WHY DO WE DO THESE THINGS".

Another technique I use is the VAXnotes SEARCH command.  You could have used:
	Notes> SEARCH "VOID FRAMES"
to get a search started.  Then enter:
	Notes> SEARCH
without an argument to find the next note with that same string.

This is slower than a directory or keyword lookup, but much faster than
scanning notes visually.

re .3

I wasn't making s smug reply, I was simply stating all you have to do is a 
little research. Not only you don't have time, but other people don't have time
to search through the notesfile for your questions. It was nice of paul that 
he had a pointer to the correct note to give you.

I added a keyword on the note in question.  Which brings me to a lesson
learned: it's a good idea to put a keyword on when you write a note that
has a detailed explanation of something and is likely to be useful for
reference much later.

	paul

    In order to understand the utilization issue at JP Morgan, I have been
    reading an article by Henry Yang and KK Ramakrishman of Digital titled
    "A Ring Purger for the FDDI Token Ring" (published 90 or 91, I have a
    very dog-earred copy" with no publication information) and it states: 
    "In the worst case, with the minimum value of TTRT and the value of D
    -> 0, the percentage loss in the maximum available bandwidth of 0.22%. 
    For a typical ring, with 20 stations, and a 4 millisecond TTRT, the
    reduction in the maximum available bandwidth is of the order of
    0.135%".
    
    Since Chung Szeto is seeing a utilization increase of 6 to 8% with a
    Network General Sniffer; I need to ask two things:
    
    Are we implementing Ring purging in the DB900's and the GIGAswitch the
    same way we did for the DB620's (in other words according to the
    paper)? or do we have a problem here?  (I'm trying to get hold of
    someone in GS engineering and the DB900 group who could clarify this,
    Anil Rijsinghani is pretty confident that we have done things properly).
    
    Is the sniffer broken?   (I read that tekalec has problems too)
    
    Have a good weekend!
    
    Tom Herendeen

	First, all DEC FDDI products use the same Ring Purger.

	Second, 6-8% used by voids DOESN'T mean that you have only 92-94%
	left for non-void frames.  As the amount of "real" (non-void) traffic
	increases, the number of void frames will decrease.

	Luc

    Paul-
    Thanks for the EXCELLENT synopsis!  and for your time too!
    
    The pointer to the original doc is appreciated too, my copy has several
    unreadable sections.
    
    Tom H.