| > Can we recommend for the customer (and engineer) some good cook books?
The best one I know is the "FDDI Handbook" by Raj Jain, published by
Addison Wesley.
> Is it possible to find an Hardcopy of the HELP ?
Not that I know of. It should be possible for you to extract and print
out specific items yourself, though.
> 1. Network utilization
> On a simple ring 2 bridges, no ring purger on we see traffic going
> regularely to 100% , why ?
The only way to find out is to put an FDDI Ring Analyzer on the network
and find out what it is that's taking up the bandwidth. Ring Purger
may be on in an end station that you may not be aware of (my guess)..
> Is it possible to have the formula used to calculate this traffic ?
Assume that:
D = Ring latency
t = total time
m = number of times the station sees the token in time t,
then
Utilization = Busy Time/Total Time = (t-mD)/t
= 1- mD/t
> 2. Traffic
> What is the meaning of:
> Traffic
> Rate/sec
> Frames = <1
> Copied = <1
> Transmitted= <1
>
> and how to compare this with:
> Frame Count fddimibMACFrameCts
> Copied Count fddimibMACCopiedCts
> Transmit Count fddimibMACTransmitCts
This should be self-explanatory: Frame rate = Received frames per second;
Copied rate = Copied frames per second (copied by the station, that is);
Transmit rate = Frames transmitted by the end station per second.
The parameters (fddimib..) that you've indicated are the actual
parameters in the end station, described in RFC-1512, which are polled
on a regular basis and compared against time to arrive at the previous
statistics. This RFC is available on ftp.digital.com in
/pub/DEC/hub900/mibs/rfc1512.txt.
> 3. What is the impact of the RING purger on the traffic. I was expecting
> that that function should decrease the traffic by purging VOID frames
Quite the opposite. This function is meant to purge no-owner frames
(consider that frames leave the FDDI ring only when stripped off
by the station that transmitted them). However, Ring Purgers
end up sending void frames to delimit. As a result under conditions
of very light traffic you end up getting a lot more void frames than
you would if Ring purger had not been enabled. This is not a standard
function.. only availabe in Digital FDDI stations. It is normally
off by default and must be enabled. Older DEC FDDI stations used
to have it on by default but we changed that because customers thought
that Void frames were actually taking up useful bandwidth which is not
the case; they are typically discarded by FDDI receive hardware in
end stations and are visible only through network analzyers. As the
"real" traffic increases, the void traffic generated by ring purger
decreases.
> 4. Explanation of what is the Report Policy ?
In short, this is a switch which allows the FDDI station to generate
Status Report Frames (SRF) upon detection of predefined events and
abnormal conditions. It's on by default.
A perusal of the above mentioned book should be very helpful.
Anil
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