question about southbridge lan adapter

[TechBoyJK]

trying to understand the concept here. I read someone talking about a motherboard that had its GigE ethernet port directly tied into the southbridge, rather than the PCI bus. To my understanding this puts the ethernet port almost as close to the cpu as ram itself. Is this right? I mean, i see the northbridge as the bus to ram, pci, etc. and the southbridge as bus to everything else... but if the ehternet is directly integrated to the southbridge, does this mean that the ethernet controller has its physical wires on the mb go directly to the southbridge chip, which goes directly into the cpu?????

THis just has me thinking that two servers with this setup would perform very well talking to each other, especially in a clustering situation, since the PCI bus won't slow the performance down as much.....

 

[TechBoyJK]

and is it feasible for a motherboard maker to design an onboard ethernet controller that has its own bus directly tied to the cpu, just like ram does? That would be kick ass ifyou could have two systems that could exchange data via 10G ethernet with a bus setup like that.

 

[Matthias99]

You pretty much hit the nail on the head.

The PCI bus has enough bandwidth (~133MB/sec.) for GbE, but just barely -- and forget it if you're also hanging RAID, etc. off of it (or if you have multiple NICs in a machine). This is where PCI-X comes in, but it's pretty expensive and sometimes still doesn't offer enough bandwidth for some applications. PCI-E ought to fix both those, but availability is still very low.

 

[Matthias99]

Originally posted by: TechBoyJK
and is it feasible for a motherboard maker to design an onboard ethernet controller that has its own bus directly tied to the cpu, just like ram does? That would be kick ass ifyou could have two systems that could exchange data via 10G ethernet with a bus setup like that.

I suppose, but at the moment this would be no faster than going through the Southbridge chip, since it has more bandwidth than 1000Mbps Ethernet does. I think that, as a general design, you'd be better off just providing lots of fast PCI-E links going forwards... that way you're not stuck with some proprietary bus.

 

[TechBoyJK]

my interest is in direct connecting a db server to a web server.

AKA, the web server has a regular 10/100 web intereface, and a GigE
interface with a direct connection to a db server with a GiGE
interface......... I was just thinking things would be that much smoother
if the bus was setup right....