After running several days with "low" RTT following a computer restart & no TB2 
connections at all, I restarted IM at the system console (not using TB2).  RTT jumped 
to the "high" value.  TB2 was loaded and running, but was not used at all.

-----Original Message-----
From: William W. Fisher [mailto:[EMAIL PROTECTED]] 
Sent: Monday, December 30, 2002 7:22 AM
To: InterMapper Discussion
Subject: Re: Round Trip Time bias

John:

I am assuming from your message that you are measuring the RTT of the 
"Ping" probe on IP. If that is not correct, please let me know.

InterMapper computes RTT by sending an echo request and recording the 
"send" timestamp.  When an echo response arrives, InterMapper records 
the "receive" timestamp. To record the "receive" timestamp on a system 
using Open Transport, InterMapper relies on the OT notifier function 
which runs at "deferred task time"... this is related to system 
interrupt time, but of a lower priority. All Open Transport notifiers 
run at deferred task time, so running InterMapper on a machine with a 
lot of network activity (ie a lot of deferred tasks), or perhaps a 
periodic processor-intensive deferred task may elongate ping times.

On classic Mac OS, Timbuktu is probably doing everything in response to 
your network commands at deferred task time, or close to it. (That's 
just a guess; I don't have TB2).



____________________________________________________________________
Note: To unsubscribe from this mailing list, please send email to:
<mailto:[EMAIL PROTECTED]> Thanks!

Reply via email to