[2161] in North American Network Operators' Group
Re: MCI
daemon@ATHENA.MIT.EDU (Wolfgang Henke)
Tue Mar 19 14:47:03 1996
From: Wolfgang Henke <wolfgang@whnet.com>
To: bajaj@bellcore.com (Shikhar Bajaj)
Date: Tue, 19 Mar 1996 11:24:27 -0800 (PST)
Cc: wolfgang@whnet.com, nanog@merit.edu
In-Reply-To: <199603191836.NAA05916@faline.bellcore.com> from "Shikhar Bajaj" at Mar 19, 96 01:36:57 pm
> > > What kinds of routers can route at near wire speeds a bunch of ports at
> > > 155Mb ATM?
> >
> > None right now. Gigarouter can handle it theoretically, but...
> >
> > I'm being picky, but it's a moot question since doing wirespeed OC3c using
> > ATM is impossible in of itself. Hell, mapping of
> > SONET framings to ATM cells take off about 6 mbps right there.
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
By the way, I did not post the above..
bajaj@bellcore.com (Shikhar Bajaj) wrote:
> A couple of minor corrections here. ATM cells are mapped into SONET frames and
> not the reverse. Also, I presume that the 6 Mbps that you are talking about is that
> the ATM bit rate over an OC-3 is 149 Mbps as opposed to the OC-3 pipe
> rate of 155 Mbps. Those 6 Mbps are taken up by the SONET management overhead
> (section, line, and path) in the frame. This is independent of whatever goes in the
> SONET payload envelope and has nothing to do with ATM.
It seems to me that Sonet OC-3 is often taken as transport for 3 DS3s,
which would reduce 155.530 Mbps to 134.208 Mbps (3 x 44.736 Mbps), less
than the 149 Mbps you cite above.
Do you have a good recommendation for Gordon Cook, TCP/IP direct over Sonet?
Thank you for posting,
Wolfgang
Wolfgang Henke wolfgang@whnet.com . http://www.whnet.com/wolfgang/
WH Networks ... ftp.whnet.com /pub/wolfgang
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