North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: ATM vs. DS3
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:[email protected]] > > > 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/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 > > > 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 ([email protected])| 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 > > >
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