[8151] in North American Network Operators' Group
Re: IP over ATM overhead
daemon@ATHENA.MIT.EDU (Eric D. Madison)
Thu Mar 13 10:50:08 1997
Date: Thu, 13 Mar 1997 10:31:46 -0500 (EST)
From: "Eric D. Madison" <madison@queber.acsi.net>
To: Stephen Balbach <stephen@clark.net>
cc: nanog@merit.edu
In-Reply-To: <Pine.LNX.3.91.970313100137.21788F-100000@bisco.clark.net>
Well Stephen,
Here at ACSI, our entire national backbone is ATM, the overhead so far
seems to be about 12-14%. This is taking into account the 48/53 byte
percentage and the time to reassemble the cells into packets at the remote
end. I have run tests in our lab and we can totally saturate a DS3 and an
OC-3 link via ATM. This is in contrast to a clear channel DS-3 which
itself loses some bandwidth to conversions and overhead. I would guess
that the difference of DS-3 ATM and clear channel is around 9% of your
bandwidth but I need to run more tests in the lab to make a more educated
guess. But you don't run an ATM backbone if your just offering IP
service, we use it to offer Frame/ATM/IP services all over the same
wire. Now, packet of sonet seems the way to go for high speed IP with
little overhead, but it is only available at 0C-3 and higher. I have not
tested it yet to see the overhead or how good it works.
Anyone out there really tested the POS cards from Cisco yet?
Eric
_______________________________________________________
Eric D. Madison - Senior Network Engineer -
ACSI - Advanced Data Services - ATM/IP Backbone Group
24 Hour NMC/NOC (800)291-7889 Email: noc@acsi.net
On Thu, 13 Mar 1997, Stephen Balbach wrote:
>
> We are installing an ATM backbone connection and wondering what level
> of overhead can be expected. Ive read from %10 to %50 - this will be a
> LAN connection so we can assume almost no cell loss. Our provider has
> said on average %12 bandwidth is overhead. It will be a Cisco->Cisco LAN
> configuration. Thanks!
>
> Stephen Balbach
> VP ClarkNet
>
