NAP/ISP Saturation WAS: Re: Exchanges that matter...

Tue Dec 17 20:57:27 UTC 1996

Craig Nordin  <cnordin at vni.net> wrote:

>> Er.  There's no such thing as perfect transport as long as TCP is
>> concerned.  If end-hosts support large windows, even a single
>> TCP session will load the network to the point where it'll lose
>> packets.

>What you say here makes sense to me.  But, out of a 500
>ping sample over the course of half a day, I was getting well
>below one percent loss -- six months ago.

Most TCP sessins are pretty short, in fact.  They simply have
no chance to open window.   Also, there's a lot of old TCP
implementations which have window limited to 64Kb (or less!).

>Now, my same sample group is going for more than three percent,
>with many ten percent loss routes showing...

Well, nobody argues that Internet is overloaded.  But the question
of how to measure the congestion is not as simple as just pinging.

The problem is that there's no reasonable way to learn loss
statistics from routers.

--vadim