*BSD News Article 48297


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From: chris@aladdin.net
Newsgroups: comp.os.linux.networking,comp.os.ms-windows.networking.tcp-ip,comp.unix.bsd.freebsd.misc
Subject: Re: Internet service providing-which OS?
Date: 4 Aug 1995 19:27:42 GMT
Organization: Aladdin Internet
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In article <B.A.MCCAULEY.95Aug3145624@wcl-l.bham.ac.uk><3upmq7$11f@agate.b, 
B.A.McCauley@bham.ac.uk writes:

>In article <3us870$15o@agate.berkeley.edu> jkh@violet.berkeley.edu (Jordan K. 
Hubbard) writes:
>>In article <3urba1$cgl@blob.best.net>, Matt Dillon <dillon@best.com> wrote:
>>>    Gentlemen.  If I remember correctly, ftp.cdrom.com is sitting on
>>>    a BARRNET T3 backbone and, on average, pulls about 6 MBytes / sec
>>>    in bandwidth.  That's on the order of 4 T1 equivalences!
>>
>>It's on the T3 backbone, but is connected to same via a 10mb/sec ethernet
>>connection which it pretty much maxes out.  1 T1 = 1.54 Mb, yes?  So
>>saying that 10Mb = 7 T1s is not that poor of an approximation.
>
>Actually I think Ethernet = 2 T1s is a better approximation. I seem to
>recall that with a random traffic profile CSMA/CD (ethernet) actually
>saturates with an average traffic at 1/e (about 37%) of the burst
>transfer rate. Beyond that, the collision retry queues just keep on
>growing.

You also have to remember that T1 is 1.5 MB bi-directional and ethernet
is 10 MB total, so even best case it's only 3xT1 = Ethernet if there is
equal traffic each way (course this is probably not the case on ftp.cdrom.com)

Chris Cain