Date: Sun, 02 Mar 2008 14:38:00 +0100 From: Willem Jan Withagen <wjw@digiware.nl> To: Barney Cordoba <barney_cordoba@yahoo.com>, Ingo Flaschberger <if@xip.at>, net@freebsd.org Subject: Re: FBSD 1GBit router? Message-ID: <47CAADB8.9000202@digiware.nl> In-Reply-To: <20080301225727.GA85851@owl.midgard.homeip.net> References: <alpine.LFD.1.00.0803012014350.20402@filebunker.xip.at> <497111.42659.qm@web63905.mail.re1.yahoo.com> <20080301225727.GA85851@owl.midgard.homeip.net>
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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
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