nanog mailing list archives
Re: ATM vs. DS3
From: Stephen Balbach <stephen () clark net>
Date: Thu, 10 Jul 1997 16:06:54 -0400 (EDT)
Question: On a Cisco with an AIP card, how do you determain what the overhead is? We connect to our upstream provider via ATM. .stb On Thu, 10 Jul 1997, Ben Black wrote:
i've never heard anything *less* than 20% loss in ATM overhead. On Wed, 9 Jul 1997, Karl Denninger wrote: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] wrote:Hello, 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 turns into: [ (53-5)/53 ] * 4 Mb/s = 48/53 * 4 Mb/s = 3.62 Mb/sEmperical 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 Sr. Engineer Nap.Net, L.L.C.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 bad. 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/ Voice: [+1 312 803-MCS1 x219]| NOW Serving 56kbps DIGITAL on our analog lines! Fax: [+1 312 803-4929] | 2 FULL DS-3 Internet links; 400Mbps B/W Internal
Current thread:
- ATM vs. DS3 Josh Beck (Jul 09)
- Re: ATM vs. DS3 Ehud Gavron (Jul 09)
- <Possible follow-ups>
- RE: ATM vs. DS3 Chris A. Icide (Jul 09)
- Re: ATM vs. DS3 Karl Denninger (Jul 09)
- Re: ATM vs. DS3 Ben Black (Jul 10)
- Re: ATM vs. DS3 Stephen Balbach (Jul 10)
- Re: ATM vs. DS3 Peter Kline (Jul 10)
- Re: ATM vs. DS3 Eric D. Madison (Jul 10)
- Re: ATM vs. DS3 Karl Denninger (Jul 09)
- Re: ATM vs. DS3 Alex.Bligh (Jul 11)
- Re: ATM vs. DS3 Dorian R. Kim (Jul 11)
- RE: ATM vs. DS3 Stephen Balbach (Jul 10)
- RE: ATM vs. DS3 Eric D. Madison (Jul 10)