Help settle an argument!

My flatmates and I are unsure as how best to upgrade our LAN.

First, I'll describe the setup we have- a Netgear DG834, to which three PCs and a Linksys WAP54G are connected. We have various wireless devices connected as well.

Now, down to the conundrum!

Two of the three wired PCs have gigabit ethernet capability, and the third is just a cheap upgrade away from it.

If we bought a gigabit switch and connected the three PCs and the DG834 to it, using the DG834 as the internet gateway and DHCP server, could we achieve gigabit transfer speeds between the PCs connected to the switch?

My flatmates say no- all data still has to pass through the router, but I'm unconvinced.

Any thoughts? Cheers.

What does "gigabit transfer speed" mean to you? If it means 1000 Mb/s actual transfers, you're in for disappointment. If it means "a fair bit better than 100 Mb/s, e.g. the range of 200 Mb/s to 800 Mb/s", then yes, just adding a consumer gigabit switch should get you faster transfers among computers directly connected to the switch using gigabit NICs.

Gigabit switches are inexpensive these days, and typically perform very well. The rest of the system, however, including the hard drives, NICs, file transfer protocols, etc., will chip away from the theoretical 1000 Mb/s to whatever transfer rates you see. 30 MB/s (240 Mb/s) is a reasonable target when just starting out with average single drives, untuned hardware, etc., and this is still a good deal faster than the best 100 Mb/s (8-10 MB/s in practice).

I've also seen lots of posts to the effect "why don't I get 100 MB/s?" Or "man, they lied to us!", which is why I try to be up-front about actual throughput experienced. Gigabit is much more challenging to the system than 100 Mb/s, so you'll easily see 80% efficiency with 100 Mb/s, but rarely with gigabit. The problem in practice is more acute with gigabit. People who deal with this stuff know this well; newcomers not necessarily.

The connections would only have to go via the router if the PCs were on seperate Networks, or VLANS. If they are all on the same network ID then the connection will be via the switch.

In order to get the increase in speed you will need to enable Jumbo frames, these are typicaly 9000 bytes instead of 1500 for the standard frame size. Its worth checking if the switch you have supports this, and if so what size it supports.

If you are getting a Gigabit ethernet card I would look at the intel ones. I just bought 4 of these. According to the reasearch I did it offers lower cpu overhead, and is very well supported.

Rob Murphy.