Re: Idle-timer reset question..

Derric Scott (dtscott@scott.net)
Sat, 30 Aug 1997 22:29:12 -0500 (CDT)

> DirecPC runs their own layered protocol for the upstream acks. It
> looks like TCP packets, except the byte count is negative. Apparently
> this makes the PM count down instead of up, making the port appear
> idle even when a lot of data is flowing through it.
>
> The DirecPC ack packets make for interesting tcpdump putput.

Interesting. I've not been able to synchronize with this customer and
check a tcpdump (that was my next step anyway).

Livingston guys - some questions along these lines:
What is the exact mechanism of the idle timer?
What would your code do with a "negative" byte count for
TCP packets, wrt the Idle timer?
Ie. does the idle timer work off of the number of bytes
thru the PM or is it reset just by the actual
presence of a packet going thru (ie. does it look
for an ascending byte count?)?
*IF* the negative byte count is the problem, can we get ComOS to
use the ABSOLUTE VALUE of the byte count? Or better yet,
just have the idle timer reset by the PRESENCE of a
packet and not be dependent on the byte COUNT at all.
Should I open a trouble ticket with support? (Ie. idle timer
broken ... ).

I'll try to get with the customer and get some tcpdump samples and also
collect evidence that there is (or is not) a problem with the idle timer.

Thanks!

Derric

-- 
Derric Scott          Scott Network Services, Inc.         P. O. Box 361353
derric@scott.net           (205)987-5889               Birmingham, AL 35236