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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical RE: gigabit router (was Re: Getting a "portable" /19 or /20)
> From: Craig Partridge [mailto:[email protected]] > Sent: Tuesday, April 10, 2001 4:36 PM > > In message > <[email protected]>, "R > ichard A. Steenbergen" writes: > > >Don't be absurd, I can walk into fry's and pick up a motherboard with > >64bit/66mhz PCI, some Netgear GA620's, and all the other > >components for a 1GHz computer for under $1000. > > OK, so your bus has 4.2 Gb/s of bandwidth. But, alas, you're in a PC > so you have to copy each packet from the line card, into main memory, > examine it, and push it back out to a line card. So each > packet consumes > twice its size in bus bandwidth. So 2 1 Gb/s line cards will consume > 4 Gb/s backplane. Assuming you can run the PCI at full rate (which in > my experience is a big big if), you can connect two Ethernets. There are a few server-class motherboards that have dual PCI-66 buses. One on each bus and there's no problem. Incidently, those same MBs usually have dual or quad CPUs. > Incidentally, this isn't the full story either. You have to > do a route lookup on each of those packets. That's typically 5 to 10 memory > accesses... 5 memory access times 1 Mpps per gigabit times 2 gigabits > is 10 million lookups per second or 100 ns per lookup. Allowing for > time spent getting through the chip to the pins, you probably > need 60 or 70ns DRAM, which is doable. Except, oops!, that completely consumes > your memory bandwidth... where are you going to find the cycles to > get the packets in and out? Huh?! We haven't had the 60ns limitation for over three years. What time-vault have you been living in? PC100 RAM is error correcting at 10ns and PC133 runs at ~8ns. In fact, I challenge you to show me where you can even buy 60ns RAM these days. That's right up there with 3 GB HDDs, not available because they can't find customers for any thing that small/slow, except propriatary applications (they make you pay ... large). I just paid $104 for 256MB of ECC PC100 RAM, at the local computer store. The discount wasn't even worth the gas/hr to drive down to San Jose for (1989 Chevy Suburban, in San Jose rush hour). > PS: Side note, this illustrates where router vendors earn their bucks. Router vendors earn their bucks by building routing/switching appliances. The fact that they manage to get corps to cough up $200K for $15K worth of hardware (COGm, generous) is yet another issue. I expect to see some serious price drops in the next 6 months. I also expect to see commodity hardware start making some serious in-roads (cause of the price-drop). COGr = 1/2 COGm, manufacturers cost of raw material (chips, labor, copper, and such) COGm = Cost of Goods manufactured (fully burdened) 2*COGm = The resellers cost (including mfg's margins) 4*COGm = The distributors price 8*COGm = Retail price (What you pay, full retail) [yeah, that's right. This means that, said RAM, cost $13 to make. econ 101] > Find a way to move data over each bus only once (double your > bandwidth!). Dual PCI66 bus. > Design your memory subsystems to keep packets and routing > data separate (increase your memory bandwidth!). PC133 ECC RAM (8ns). > Find a processor that > doesn't waste cycles doing virtual memory (improve your memory access > times!). Dual/Quad 1Ghz PIIIs, anyone? > Oh yes, and then add hot board swap, How many routers actually do this? Even when they do, it is more prudent to find the time to shut it down for 5 minutes. It's not like solid-state devices die all the time...no moving parts. Keep them cool and they'll go obsolete before they fail. Unless it's a combat situation (where you don't have time to swap anyway) there isn't much that warrants this level of maintenance. You're much better off with a redundant hot fail-over configuration so that you can bring one down for PM and replacement/upgrade. > a working BGP implementation (quick, where's Tony Li working these days:-)), I actually like GateD. It ain't fancy, but it works. > a CLI, Linux is handy. RT Linux might be better (maybe). > and a power subsystem for a CO, If you must include that, then my choice is a Liebert GT3600. > and you're in business. With current commodity price drops, in less than 6 months, the cost of doing this will fall well below $1000, retail. Considering potential market volume. A 100% proprietary hardware solution may not be feasible, at that price-point. They will *have* to use commodity hardware, just to keep up the margins.
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