The nit I'm picking is inline... (I'm feeling like chipping in tonight)

>>> "The Long and Winding Road" 
02/17/03 06:13PM >>>

[snip]

if I have a 75xx router with 300 ethernet ports, and I bridge all
those
ports, do I have an L3 switch, or a router?

[KD]
You have a router performing L2 operations (forwarding, switching,
bridging -- whatever).  Would a cheap Linksys switch be faster?

What makes a L3 switch in my mind is where the forwarding happens.  If
the L3 CPU (new way to look at it?) has to handle every packet, that's a
router.  If the first L3 packet is handled by the CPU which then
programs ASICs to handle the rest of the flow without bothering the CPU,
that's an L3 switch.  Is there a difference from a packet/network
perspective?  No.  The L2 headers and L3 headers are all properly
updated in both cases (at least we *hope* they are) and traffic is
delivered most of the time.  (If it was delivered all the time, networks
wouldn't need us to fix them)  :-)

What does this mean to us?  Not much other than for capacity planning. 
IMHO, an L3 switch has a longer life than a router.

When I design networks, I don't think L3 switch.  I think about routers
interconnecting L2 segments.  I even draw them that way most of the
time.  :-)

My advice to those having problems with this subject:  Replace every
occurrence of "layer 3 switch" with "router".

[/KD]




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