mailing list archives
Re: ATM vs. DS3
From: Karl Denninger <karl () Mcs Net>
Date: Wed, 9 Jul 1997 22:52:00 -0500
On Tue, Jul 09, 1996 at 10:38:57PM -0500, Chris A. Icide wrote:
On Wednesday, July 09, 1997 9:34 PM, Josh Beck [SMTP:jbeck () connectnet com]
I just thought of something. We are in the process of purchasing a
4 Mb CIR from another backbone. Now, we have the choice of ATM or standard
T3 delivery (over a DS3 either way). Now, if we get ATM, that 4 Mb CIR
[ (53-5)/53 ] * 4 Mb/s = 48/53 * 4 Mb/s = 3.62 Mb/s
Emperical data shows that we are currently losing about 20.5% of capacity
to IP over ATM overhead on fairly aggregated traffic. This means that *IF*
your new connection is being measured as 4Mbps of cell bandwisth, you
will only be getting 3.18Mbps. You may want to verify from the company
providing this link what exactly are they limiting you to?
btw, the extra overhead is lost in things like the last cell of a packet not
being full, etc.
Chris A. Icide
My God, someone admits it?
I've used 20% as the general ATM overhead now for almost two years, and have
been poo-pooed by lots of people claiming that it wasn't anywhere near that
Funny how it all comes out in the end. :-)
Karl Denninger (karl () MCS Net)| MCSNet - The Finest Internet Connectivity
http://www.mcs.net/~karl | T1's from $600 monthly to FULL DS-3 Service
| 99 Analog numbers, 77 ISDN, http://www.mcs.net/
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Re: ATM vs. DS3 Vadim Antonov (Jul 10)
Re: ATM vs. DS3 William Allen Simpson (Jul 10)
Re: ATM vs. DS3 Avitosh Pal (Jul 10)
RE: ATM vs. DS3 Chris A. Icide (Jul 10)