FBSD 1GBit router?

[Willem Jan Withagen]

Erik Trulsson wrote:
>> Ok, well I've never seen a router with 1 port.  I
>> thought we were talking about building a router? 
> 
> He did not say anything about a single port router.
> He talked about single port network cards.  You can
> use more than one of them when building a router.

Well lets nitpick.
A router does not have to have 2 ports.
2 examples:
  - routing between VLANs on the same interface
  - when doing routing in an overlay network.
	EG. in a connecting VPN networks

I'm looking for a stream exploder.:)
1 2Mbit stream in, and as many as possible out.
And 7*1Gb = 14Gbit, so I'd like to be pushing 7000 streams.
(One advantage is that they will be UDP streams, so there is
a little less bookkeeping in the protocol stack )

>> The lack of PCIe cards is a good reason to consider a
>> PCIX machine.
> 
> What lack of PCI-E cards?  These days there are quite a
> few to choose between.

I'm under the impression that PCI-E is the way to go. Especially if I 
look at what is implemented on the more serious server boards.

>> On the systems that we have, the 1x PCIe
>> ports are a lot slower than a PCI-X card in the slot.
>>
>> 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.
> 
> What contention issues?  With PCI-E each device is essentially on its own
> bus and does not need to contend with other devices for bandwidth on that
> bus.

Right, in PCI-E the lanes are just a star network into a hub.
Now there is always going to be a bottleneck in a network. So here the 
big chance is that this is between the CPU and the hub.
To see that just complete the above math:
  7000 stream @ 2mbit/sec =~> 1.25E6 p/s
                          =~> 1,75   Gb/sec

Where all datatransport has to go over the processor. Well I have not 
seen systems with this as Frontside bus, so this is going to require a 
carefully crafted design. :)

--WjW