network throughput

[manwithplan]

is it normal to not get the maximum through put on a network as is quoted in the specs?

I ask because I just tested the throughput on our home lan (2 systems) and Instead of getting 9.odd Mbps it was fluctuating between 6.5 and 7Mbps. Surely this aint right?

Im running a 3com 3c905b-tx nic and my dads sytem has a 3csoho100-tx. The hub is a 3com 'officeconnect ethernet hub 4' which is only supposed to run at 10Mbps, im not expectin to get 100Mbps out of it even if the cards can do that speed!

cheers
c.

 

[ScottMac]

70% of rated speed is very good for a hub-based system.

yer doin' OK.

FWIW

Scott

 

[Garion]

With a switch, you might get closer to the rated speed, but hubs "share" the bandwdith - A switch is a highway with one lane per car - Go as fast as you want, to the capacity of your car. With a hub, all the cars are sharing the same lane. Too much traffic, things slow down.

- G

 

[Techwhore]

You'll never see the speed as rated on the box. There are a few possibilities and reasons as to why you won't, the biggest being TCP overhead.

The difference between TCP and UDP is that TCP sends routing information such as MAC address or IP address and attempts to determine the quickest path from point A to B. This mitigates packet loss and provides a more stable means for sending data over networks.

 

[ScottMac]

The basic difference between UDP and TCP is that UDP just blindly sends the packets (relying on a higher layer for delivery acks), TCP uses it's own mechanism for reliable delivery. The routing and path stuff happens somewhere else (in IP / L3).

FWIW

Scott

 

[Nothinman]

Also make sure hard disks on the systems doing the transfers can keep up, I've had more than one system where the network was faster than the hard disks for straight throughput.