Slow Gigabit LAN

Hussman

Hussman

Hussman

Associate
Joined
1 Nov 2003
Posts
1,272
Location
Maidstone, Kent
Hi,

Having a bit of a problem with a slow LAN.

Image1.gif


My LAN is shown in the picture. It consists of 3 PCs connected to a Netgear Gigabit hub(http://www.netgear.com/Products/Switches/DesktopSwitches/GS605.aspx)

This is connected to my Netgear ADSL Firewall Router DG834
(http://www.netgear.com/Products/RoutersandGateways/WiredRouters/DG834.aspx)

A Netgear wireless access point, WG602 is connected to the router
(http://www.netgear.com/Products/BridgesAccessPointsandExtenders/AccessPoints/WG602.aspx)

Finally, I have a gigabit NAS connected to the hub too.

I believe this set up should allow me to access data on any of my PCs, or from the NAS, at gigabit speed.

However, if I run Task Manager when copying a file the maximum network usage I get is around 12%

I have switched on jumbo frames on all the network adaptors, but with the same result.

Thinking it could be the hdds slowing my network down, I installed Sandra.

The network speed test there came back as below.

Image2.jpg


The cable used is cat5e, over a distance of about 10-15 metres maximum.

Surely this is wrong?

Any ideas....???

Thanks in advance.
 
It depends upon the hardware on the machines, at gigabit speeds you are hard drive limited. For example from my laptop the max I can get is about 200Mb/s. PC to PC with a standard SATA disc running at 7.2k RPM I wouldnt expect more than about 400Mb/s
 
slightly off-topic (sorry)
what gigabit nas are you using?

//i have the same switch and router dg834g

i have gigabit smc network cards

i found enabling jumbo frames paradoxically slowed everything down

try running sandra again with jumbo frames off on all the network cards
 
have you tried sisandras harddrive benchmark to see what your harddrive is capable of?
also what network cards have you got ?
 
Make sure task offloading is enabled.

Also are you using GigE PCI cards? Or do the motherboards have GigE built in?
 
Hi,


Thanks for the replies.

Turning off jumbo frames on all PCs and the NAS has increased Sandra through-put to 52Mb/s.

However now when I use task manager to check for network activity it sticks at around 8%. With jumbo frames enabled it was around 12%.

All the devices are using on-board gigabit, not separate cards.
 
I wouldn't worry about what your network utilisation is at.

50-odd MB/sec is a fine speed for normal HDDs writing/reading accross the network and with onboard GigE nics.

If you're transferring with FTP soft, be sure to check out different servers and mess with their packet settings as this can make a huge difference to maximum throughput.

By the sounds of things, you've got the driver and hardware side of things pretty much nailed.

Might be worth setting your nic to "optimise for throughput" rather than cpu if you want to squeeze every last bit of speed out of it though I tend to do fine with the cpu option.
 
It seems odd that JF support causes such problems when the switch is GB and specifically lists JF support. 52 is about right though so i'd not worry too much about it. Are you 100% sure the onboard lan has full support for GB with JF ? Perhgaps try PC to PC with a x over with & w/out JF, that would totally eliminate the switch at least ?
 
Good point but most cards will work with Cat5e tbh, and if it's topping out at 52mbit it's doing Gb speeds so it's probably not cable related. Cat6 is now becoming more common though (6 was cheaper than 5e when I last ordered cables for work).
 
growse said:
Only if you're made of money. Cat5e works just as well.
Click to expand...

Strange, i'm sat here (at work supposedly) fileing purchase orders and last week we ordered a batch of cables....Cat6 is either the same price or cheaper that the 5e stuff and we are talking under £2 for 15m of pre made cable, how's that made of money ?
 
Avalon said:
Strange, i'm sat here (at work supposedly) fileing purchase orders and last week we ordered a batch of cables....Cat6 is either the same price or cheaper that the 5e stuff and we are talking under £2 for 15m of pre made cable, how's that made of money ?
Click to expand...

It's about 1.5 times the price where I'm based. I suppose different suppliers will try to get their premiums on different things. If cat6 is cheaper, then get that :)
 
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