what is actual thruput of gig to the desktop?

[ja1064]

a CCIE i use for consulting was discussing our plans to replace five 3548 XLs. We were thinking to go all gig. He explained that the PCI bus of a PC would not actually allow more than 200Mb of throughput. Is this legitmate? If so i would question the price for a gig switch to "double" the pipe which i question would be felt by our typical office automation user. We don't do CAD nor much streaming media or other high bandwidth apps

[bjw]

I think that saying PCI bus is limited to 200Mb thoughput might've been true for platform x with chipset y, on motherboard z, but it's not necessarily always factual.

Example, Vendor A's 64 bit, 133mhz PCI front-side bus architecture can have a published throughput of 1Gbps.

However, this the the throughput for the entire PCI bus. PCI Bus contention and hard disk drive operations for multiple devices will all share slices of the bus capacity.

So in effect you could loosely say that a certain 133mhz PCI front side bus (FSB)has the capacity of 1 Gbps, a 166mhz PCI FSB is about 1.2 Gbps.

http://www.quatech.com/support/comm-over-pci.php

Just keep in mind that manufactures have different ways of clocking/over-clocking PCI bus speeds and you may consider looking at your PC/Server vendor's specifications.

[bjw]

Here's a couple of interesting test articles:

http://redmondmag.com/features/article.asp?EditorialsID=311

http://www.enterprisenetworkingplanet.com/nethub/article.php/3485486

[bjw]

And one last reference:

http://www.cs.um.edu.mt/~ssrg/wallace.htm