Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!think.com!yale!cmcl2!kramden.acf.nyu.edu!brnstnd
From: brnstnd@kramden.acf.nyu.edu (Dan Bernstein)
Newsgroups: comp.unix.admin
Subject: Re: IRC Net Bandwidth (was IRC and Security)
Message-ID: <16929:Mar2121:19:0091@kramden.acf.nyu.edu>
Date: 21 Mar 91 21:19:00 GMT
References: <5152:Mar1805:08:4291@kramden.acf.nyu.edu> <703@seqp4.UUCP>
Organization: IR
Lines: 27

In article <703@seqp4.UUCP> jdarcy@seqp4.ORG (Jeffrey D'Arcy) writes:
> brnstnd@kramden.acf.nyu.edu (Dan Bernstein) writes:
> >But it's the packets that cost. A 2-byte packet costs almost as much as
> >a 500-byte packet.
> Yeah, right.  On an Ethernet, you have a 14-byte Ethernet header, 20-byte
> IP header, 20-byte TCP header, a couple of trailers...all told less than
> 60 bytes, and I can't imagine other data links are that much worse.

By far the largest cost of a packet on the Internet is the cost of
routing. If we upgraded NSFNET to trillion-megabyte-per-microsecond
links, connections over it would run perhaps a few percent faster.

You can shout all you want about ``data links,'' but there aren't any
fixed data links in the Internet except on local networks. How much IRC
data do you think *doesn't* get propagated outside its local network?

> That
> would seem to make a 500-byte packet about nine times as costly as a 2-byte
> packet in terms of transmission time.  Certainly there are per-packet costs
> regardless of the packet length, but not enough to make your statement even
> nearly true.

Rather than making up statistics, why don't you measure what actually
goes on? The cost per byte is very small compared to the fixed cost per
packet.

---Dan