From: p729@xxxxxxx
Date: Wed Jun 05 2002 - 04:17:44 GMT-3
In today's world the differences are largely semantics and marketing. Many of t
he qualities you cite for each are certainly true, but a layer-3 switch that un
derstands routing protocols is still a router to me, but marketing types would
call this thing a "routing switch." Okay...
The distinction between routers and switches sort of comes into relief if you l
ook back at how switches evolved over time. Switches always implied fast logic,
but before the advent of "routing switches," many so-called "layer-3 switches"
still needed a "real" router to talk to other routers and figure out how to sw
itch the first packet at layer-3. The "layer-3 switch" would then cache the rou
te and henceforth switch to it at "switching" speeds (like fast switching in Ci
sco routers).
But now everything is fast and has lots of memory. We can make tons of those "f
irst layer-3 packet" routing decisions ahead of time and cache it and hash it a
nd call it CEF. We can look deep into packets at "wire speeds" and make all sor
ts of routing decisions based on, uh, the contents of the payload..."content" r
outing...
Regards,
Mas kato
https://ecardfile.com/id/mkato
============================================================
From: "Kumar Dasari" <kdgroup@plts.gtulink.edu>
Date: 2002/06/05 Wed AM 01:51:51 EDT
To: <ccielab@groupstudy.com>
Subject: A router and Layer3 Switch
Hi folks:
I am trying to get this straight in my head. What actually is the difference
between a router and a layer switch? Reading from trade magazines and such
this is what I thought.
1. Routers tend to have interfaces from unlike media (so, are actually doing
protocol translation also?) while the layer 3 switches tend to have higher
port density but primarily with like media (may be FastE to GigE at the most).
2. Routers tend to switch packets between the interfaces but still CPU based
processing is involved thus are software based where as l3 switches use Asics
for switching between the interfaces so are hardware based.
3. Routers for WAN and Layer 3 Switches for LAN/MAN
4.Routers tend to package enhanced services like security and Qos and such
while the L3 switches are optimized to low latency packet switching engines.
May be I was somewhat redundant, but that is what I would have said if
somebody asked me the same question. Am I thinking right here? Please comment.
Because lot of products on the market today seem to defy this and, I am
thoroughly confused.
KD
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