IP: Re:: The Tidal Wave Is Forming

[Dave Farber <farber () cis upenn edu>]

To: farber () cis upenn edu
cc: mo () UU NET
Subject: Re: IP: The Tidal Wave Is Forming 
Date: Thu, 05 Nov 1998 12:18:33 -0500
From: "Mike O'Dell" <mo () UU NET>


sigh....

the assertion of "IP over glass without SONET" is at best
technically suspect.  that's because there are two uses of
the term SONET.  there is SONET-the-line-coding and
SONET-the-network-architecture.  the packet interfaces of
all known routers that drive fast glass in
non-gigabit-ethernet-mode (ie, OC12c, OC48c, and OC192c)
absolutely do use SONET-the-line-code to make the bits of
the framed packet march down the glass. that's why the IETF
standard describes Packet-over-SONET, or POS.

whether or not the packet goes through a SONET terminal at
bit-synchronous speeds is generally not architecturally
interesting.

from an operations standpoint, however, many people find
the diagnostic and monitoring abilities of SONET terminals
to be very valuable for operating a glass plant even when
the network paths in question are not using
SONET-the-network-architecture to do transparent path
restoration. this mode is sometimes referred to as
"point-to-point SONET" or "dark SONET".

so while it seems to be au courant to talk about SONET-vs-FOO,
that is at best a dubious dichotomy.  

        -mo


_____________________________________________________________________
David Farber         
The Alfred Fitler Moore Professor of Telecommunication Systems
University of Pennsylvania 
Home Page: http://www.cis.upenn.edu/~farber