Re: TTL values and CU-SeeMe

Jason Williams (streak@ccwf.cc.utexas.edu)
Fri, 12 Jun 1998 00:08:07 -0500 (CDT)


On Thu, 11 Jun 1998, The Mad Scientist! wrote:
> Basically it can affect both TCP and UDP traffic. I thought it may be a
> factor in packet loss, choppy audio and slow/jerky video under CU-SeeMe.
> I'd be interested to hear Brian Godette's comments on this one.

Nice little article though I'm not sure it affects many people within the
US though I could be wrong. It's been my experience..that if the # of
hops reaches 30 on a traceroute, there are many more problems than just
the TTL. The delay from each router is signicant and adds up to the total
delay that causes packet loss. If anything, the only difference for those
people who can't reach places within 30 hops, is EXTREMELY SLOW
response instead of no response at all. More than likely, CU will timeout
long before the slow response is realized.

I remember back around 1994 or so, I could traceroute from one end of the
US to the other end and never experience a delay longer than 40ms per
router. Now it seems delays of >1000ms are becoming quite common. I
remember reading somewhere long time ago that real-time traffic starts to
have problems with delays of more than 100ms total. (I believe that was
in reference to IHHD...the Internet Head to Head Daemon for playing games
thru the net).

I've done a fair share of tracerouting...and I've never seen the # of hops
exceed about 20-24 or so. But it depends a lot on where you're
tracerouting to.

--
streak@ccwf.cc.utexas.edu    * Jason Williams -- Austin, Tx.  |     |
streak@mail.utexas.edu       * University of Texas at Austin  | ___ |
streak@cs.utexas.edu         * BS Computer Science             \_|_/
*************** http://ccwf.cc.utexas.edu/~streak/ **************|