FBSD 1GBit router?

[Niki Denev]

On Sun, Mar 2, 2008 at 5:11 PM, Ingo Flaschberger <if at xip.at> 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-e: 2gbit/lane
>
> > 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
>
>

André Oppermann's excellent paper has even more info to why PCIe is
better than PCI-X for networking :

http://people.freebsd.org/~andre/Optimizing%20the%20FreeBSD%20IP%20and%20TCP%20Stack.pdf


--Niki