🚀 go-pugleaf

In article <59793@bbn.BBN.COM> craig@ws6.nnsc.nsf.net.BBN.COM (Craig Partridge) writes:
>
>He computes the max delay and average efficiency for 500 stations with
>TTRT at 8ms as 8 secs and 75%.  But if, as he suggests, you keep
>yourself to a max of about 100 stations, max access delay is about
>0.8 seconds and 86%.  (If you are willing to get smaller, down to
>around 10 stations, its 0.15 and 99.5%).
>
If you are a vendor like Silcon Graphics, you have to take the worst case 
scenario (i.e. 500 stations) into account.  If you are an architect and
systems integrator of turn key real-time control systems like myself, you
focus on your clients actual requirements.  These are typicaly 15 to
60 stations of which 2 to 10 exchange real-time data (i.e. access
delay must be less then some Tmax where Tmax is application dependant but 
typicaly under .5 sec) and the rest require interactive response times
with a max delay under 1 sec.  In this scenario TTR protocols appear to
be a viable alternative.

Larry Levin
Information Systems-Engineering Center
SRI International,  Menlo Park CA.
levin@istd.sri.com