Cell Relay Archive

[craigp@world.std.com (Craig Partridge)]

Mahmoud Kayali <mahmoudk@ee.ubc.ca> writes:

>Does anybody know what the term " IP Switching " means. I am looking for
>some decoumentation about it.

It has been interesting watching this exchange and comparing it with a similar
one on comp.protocols.tcp-ip.  The answers differ in various ways.

So, for comparision, below is the definition of IP switching I posted to 
comp.protocols.tcp-ip in response to a similar question.

 From: craigp@world.std.com (Craig Partridge)
 Subject: Re: IP switching
 Message-ID: <Dzw5q0.3Dw@world.std.com>
 Organization: The World @ Software Tool & Die
 References: <3270F962.7BFB@cmg.nl>
 Date: Sat, 26 Oct 1996 16:27:36 GMT
 Lines: 37
 
 "Mark R. Kuijper" <Mark.Kuijper@cmg.nl> writes:
 
 >Could anyone explain in short what "IP switching" is. Any references to rfc's,
 >or literature are welcome !
 
 I'm aware of two definitions:
 
     1. An approach to building IP routers that attempts to bypass normal
     IP routing by specially marking and pre-routing a large fraction of
     the datagrams passing through a chain of routers.
 
     [Most recently an idea made popular by Ipsilon (www.ipsilon.com).  Cisco
     has recently introduced a variant called "tag switching" (see their
     proposals in ftp.ietf.org/internet-drafts/ -- look for a document
     by Fred Baker and Yakov Rekter).  I believe the first such scheme was
     developed by Tracy Mallory in the late 1980s and used on the BBN
     Butterfly routers -- it was presented at an IETF plenary in 1987 or 1988].
 
     2. Any router built around a switched backplane rather than a shared bus.
 
     [Various schemes exist.  One good example is the NetStar (now Ascend)
     GigaRouter].
 
 Note the two definitions are orthogonal.  Definition (2) describes how you
 move data within the box, while definition (1) describes how you decide
 where the data should be moved.  One can build a router that satisfies both
 definitions, but you don't have to...
 
 I'll observe that a previous poster indicated that "IP switching" was just
 another word for old-fashioned "IP routing."  This is true of definition (2)
 but *not* necessarily of definition (1).  "IP switching" under definition (1)
 is a technique that attempts to bypass standard routing to achieve higher
 performance.  The risks one takes in bypassing standard routing to achieve
 the potential performance gains is an important issue that one needs to be
 aware of.
 
 Craig