Thus spake Dennis
>Boy, you guys have been reading a LOT of cisco propaganda, aren't you?
>Ciscos are just a PCI bus, and they are generally deficient in cpu power.
Uhm, no. They make considerably use of PCI busses in a lot of places,
but not all.
>The higher end ciscos (7500 and up) have 2 busses, but at 15 times the cost
>of a PC its hardly worth if for twice the bus bandwidth.
Uhm, no again. The 7500 VIP cards have a PCI bus for each of the two
PA's that would be installed on the VIP card...the bus between the VIP
card and the backplane (and RSPs) is considerably higher speed than PCI.
>Even though ciscos can "switch" they still are routing unless you are on
>the same card.
And you've been reading a lot of marketing material from "layer 3
switch" vendors, haven't you. :)
"Switching" is really a fairly generic term. To be more precise, you're
either routing or bridging. Switching is purely just the act of taking
a packet from one interface and sending it out another interface.
Routing is switching a packet between interfaces based on the layer 3
information, so yes, even those "layer 3 switches" are really
routers...they're just routers implemented with ASICs rather than in
software. Bridging is switching packets based on layer 2 information.
The term "switching" devoid of any greater context, is *typically* used
to indicate bridging, and the term "switch" devoid of any greater
context is really a multi-port bridge (as I mentioned in an earlier
post...a classic "bridge" has only 2 ports).
But, to answer the greater point to what you said above...even
"switching" packets (whether bridging or routing) between cards on a
75xx or higher, doesn't necessarily involve the main CPU of the router,
the VIP cards can (if configured to do so) make the "switching" decision
on their own, with the main CPU (on the RSP) only processing routing
protocol information, CLI logins, and building and distributing routing
and forwarding tables out to the VIP cards.
>Any kind of LAN/WAN routing has the same issues on a cisco box as on a
>PC.
Not necessarily.
>Performance-wise, ciscos have virtually no advantage below 12000 series.
>They do have a big lead in software maturity however.
I would disagree. I'd say there is a fairly significant performance
advantage in the 75xx's as well due to the significant backplane
capacity (significantly higher than PCI), and the multi-cpu design (not
SMP which Linux can do, but dedicated co-processors essentially). As
you add more cards in a 75xx, the packet switching capacity (up to the
limit of the backplane capacity) goes up.
>Dennis
>http://www.etinc.com
>ISA and PCI T1/T3/V35/HSSI Cards for FreeBSD and LINUX
>Multiport T1 and HSSI/T3 UNIX-based Routers
>Bandwidth Manager
Ah...now I see the bias. ;)
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IgLou Internet Services (800) 436-4456
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