On Sun, Mar 02, 2008 at 04:11:28PM +0100, Ingo Flaschberger wrote: > Dear Bareney, > >>> And back to 1x is not fast enough: >>> There are no 1gbit single port network cards that >>> support more than 1 >>> lane, even if you plug it into a 16 lane slot. >>> (and I'm not talking about 10gbit cards; if you have >>> 10gbit upstream you >>> have enough $$ to buy good gear) >> >> Ok, well I've never seen a router with 1 port. I >> thought we were talking about building a router? > > Have you ever read the link? > Have you noticed that the axiomtek appliance has 7 gigabit ports? > Each one connected with 1 lane pci-e? > >> The lack of PCIe cards is a good reason to consider a >> PCIX machine. On the systems that we have, the 1x PCIe >> ports are a lot slower than a PCI-X card in the slot. > > Perhaps, but: pci-x: 4gbit for the whole bus system.
PCI-X actually has up to twice that: 133 MHz * 64 bits = 8.512 Gbit/s ( = 1.066 GB/s ) That's assuming only a single PCI-X device on the bus. If you have two devices connected to the same PCI-X bus then most motherboards will lower the clock frequency to 100MHz for reliability reasons. If there are 3 or more devices connected to the same PCI-X bus then the clock frequency is usually lowered to 66 MHz. (Yes, the more devices you connect to a PCI-X bus, the less bandwidth you get to share among them.) > pci-e: 2gbit/lane In each direction. The total bandwidth available is 4Gbit/s per lane. (This is similar to Gigabit ethernet which can only send 1Gbit/s in each direction, but can send and receive at the same time, thus using a total bandwidth of up to 2Gbit/s.) > >> You need 4Gb/s of throughput to handle a gigablt >> router. (1 GB/s full duplex times 2). 1x is 4Gb/s >> maximum. In my view, you always need twice the >> bandwidth on the bus to avoid contention issues. > > sample1: > 3 pci-cards: > card 1: 1x = 2gbit (dedicated) > card 2: 1x = 2gbit (dedicated) > card 3: 1x = 2gbit (dedicated) > -------------------- > sum: 6gbit > (but the use only 3) > > sample2: > 2 pci-x cards > card 1: 4gbit (shared) > card 2: 4gbit (shared) > card 3: 4gbit (shared) > --------------------- > sum: 4gbit > > homework: > calculate with 7 ports. > > Kind regards, > Ingo Flaschberger > > _______________________________________________ > freebsd-net@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-net > To unsubscribe, send any mail to "[EMAIL PROTECTED]" -- <Insert your favourite quote here.> Erik Trulsson [EMAIL PROTECTED] _______________________________________________ freebsd-net@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-net To unsubscribe, send any mail to "[EMAIL PROTECTED]"
