For the record: Layer 3 switch = Multilayer switch (I say this because I
like to use the term Multilayer switch rather than Layer 3 switch... dunno
why... I guess because in the switch/routers, you actually use and configure
Multilayer switching)
In reply to some of the other posts on this topic:
>This is actually covered in under the switching portion of the CCNP..
>Here is a link from Cisco for you to reference:
>http://www.cisco.com/warp/public/cc/so/neso/lnso/cpso/l3c85_wp.htm
Layer 3 switching (Multilayer switching) *is* covered on the CCNP Switching
exam and I don't know how one could pass it without an understanding of how
it works. (although that link that was provided pointed to a page that
didn't explain MLS very well at all)
> One differance is that a layer 3 switch does wire-speed switching
AFAIK, *all* switches perform wire-speed switching, as long as the backplane
isn't oversubscribed (even then what gets switched is done at wirespeed and
other stuff is dropped). Can someone make sure I'm not fibbing or confused
on this?
>Okay, two things -
>
>One - abduct a Cisco marketing rep, tie them to a chair, shine a bright,
hot
>light in their face and ask *them* what the difference is.
>
>Two - while they're tied up, ask them what "wire-speed" is supposed to
mean.
Wire-speed simply means that the data is switched across the backplane to
the destination port ASAP, as fast as the wires can carry the data thru the
ASICs and to the destination port. I.E. the speed of light (minus a small
fraction because the wires do actually have a non-zero resistance =)
>Someone may have a product based answer for you but literally a router is a
>layer 3 switch. Just think of all of the functionality that a switch
offers
>you and add on the route switch module to sweeten the pot.
>A router either bridges or has separate subnets on each of its
>interfaces.(simplistic answer of course).
This is very misleading. Although a router has a switching process within
it, and that switching process can take on many forms, a router is NOT
simply a Layer 3 switch. Although a router can bridge (including bridging
VLANS using Integrated Routing and Bridging), even then it is not the
equivalent to a switch because of the way it performs the process (in
software on a CPU instead of with an ASIC). The router doesn't keep a CAM
table like a switch, etc. and without something like a NetFlow Feature Card
or MLS processor, a router can't bridge (switch) at wirespeed like a true
Layer 2 switch...... Even on a switch/router with a NFFC or the like,
without Multilayer switching enabled, it's like a router with a ton of
ethernet (or whatever) interfaces. The packets are NOT routed and forwarded
out at wirespeed like they are (after the first packet) when Multilayer
switching is enabled and configured.
I by no means am the expert on Multilayer switching, and I'm not trying to
flame anyone for their answers. But there were alot of things being said
that didn't answer the original poster's question (actually the one post by
Bob Salazar was correct, but he didn't mention that you have to actually
turn on the Multilayer switching fuctions on the hardware he listed) or that
were misleading. I'm sure there are some things that I messed up or just
don't have a full understanding of (like "wire-speed hehe), so comments are
welcome.
Mike W.
"Denton, Jason" wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> Can anyone tell me what the REAL difference is between a layer3 switch and
a
> router?
>
> Jason
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