>On Mon, 28 Feb 2000, Nick Bastin wrote:
>
>> Exactly. The 7206VXR will still outperform a high end linux system,
>> because there are other demands on the bandwidth of the PCI bus in your
>> linux system. Also, it's worth noting that while Cisco classifies the 7200
>> series in their 'High-End Routers', it's a cheap box intended for
>> enterprise work. The newer 7576 can push 4Gbps sustained across the
>> chassis, and even the older 7507/7513 can do 2Gbps. I'm not suggesting
>> that we'll ever get linux to touch the capabilities of a 12000 (or a
>> Juniper M20/M40), but PC hardware issues aside, the kernel ought to be able
>> to push packets as well as any Cisco 7xxx series router.
>
> This is not what I said. What was said is the 7206VXR with
>the 300Mhz NMP has *exactly* the same limit as a high end PC...
Well, yes, that wasn't what I meant by exactly. I was simply referring to
the last comment you made about sharing PCI bus bandwidth. Yet another
communciations breakdown caused by email.. ;-) (Maybe I should have put a
however after the exactly?)
> The difference is the Linux box will do this in the slow path,
>and keep doing it while filtering the traffic, the 7206 dies of NMP
>overload.
Except, obviously, if you're smart about the modules you run in the 7206,
you'll never have to worry about hitting this limit. Same goes for the
linux box, except I can be sure that the 7206 will really pump 600Mbps,
whereas the PC is susceptible to things like lousy chipsets that can't
utilize full bus bandwidth and the like. You can get a PC that will
perform as well as the 7206 at the bus level, but you can't use just any PC.
> What other demands? A Linux based router is running a bunch
>of cards, not disks/etc.
Well, on most of my firewalls/routers, I have a PCI video card. It might
not be doing much, but it's still sucking up some bus bandwidth. Also, if
I'm running disk at all for some reason, the IDE controller is on my PCI
bus too. I tend to run disk on the firewalls, and not on the routers,
although that's mostly a semantic distinction (the firewalls do logging,
the routers don't, although I could do this over the network too...)
--
Nick Bastin
Software Developer
OPNET Technologies
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