Gigabit transfering at 100mbit/s

[splice]

Hopefully someone here can help me out.

I currently have the following setup:

Switch 3Com (5-port 100/1000mbps) (basement)
SageTV Server (1Gb)
Ubuntu Server (100Mb)

Switch 3Com (8-port 100/1000mbps) (main floor)
HDHomeRun (100Mb)
Linksys Router (100Mb)
SageTV HD Extender (100Mb)
Basement Switch (1Gb)
Upstairs Switch (1Gb)

Switch trendnet (5-port 100/1000mbps) (upstairs)
Printer HP2600n (100Mb)
Printer HP3310 (100Mb)
Work Computer (1Gb)

So, the servers are connected to the basement switch, which is connected to the main floor switch, which is connected to the upstairs switch.

All of the computers that have gigabit show that there are connected to the switch at gigabit speed, but when I transfer files from the sagetv server in the basement to the Work computer, the transfer speed maxes out at 100mbit (showing ~8% network utilization of the 1Gb connection in Windows). Is there something about when having a mixed network with 100mbit and 1gbit that all transfers are locked to 100mbit max speed?

Anyone have this problem, or experiencing the same issue?

 

[Red Squirrel]

you need to enable jumbo frames and increase MTU to take advantage of gigabit. I learned this the hardway, upgraded my network to gigabit only to find out I can't use it at it's fullest. (I need to be able to plug any random PC into my network and have it up, so I can't be changing settings on each PC).

Someone with more experience then me with this may be able to give more details, or perhaps a work around.

 

[perdomot]

How would enabling jumbo frames impact P2P programs like bittorrent when downloading video files? I get a lot of subbed anime shows and am always looking to improve speeds.

 

[Madwand1]

Originally posted by: splice
Is there something about when having a mixed network with 100mbit and 1gbit that all transfers are locked to 100mbit max speed?

Yes, there is a potential issue if you're downloading from the same local server at the same time using a mix of 100 Mb/s and gigabit clients / paths. To diagnose this further, you should ensure that only one client is active and measure the underlying network performance without doing file transfers.

Network performance can be measured with various tools, e.g. iperf version 1.7:

server: iperf -s
client: iperf -c server -l 64k -t 15 -i 3 -r

And no, you don't have to use jumbo frames to get good performance over gigabit, although it can help significantly at times, especially with old or low-end hardware.

 

[her209]

What type of hard drive setup are you running?

 

[JackMDS]

Use TCP Optimizer to optimize the TCP/IP according to the Type of the Internet connection.

http://www.speedguide.net/downloads.php

Do Not increase the MTU above the 1492 or 1500 (i.e. do not use Jumbo frames) just double the value of the RCwin.

http://www.ezlan.net/network/TCPoptimize.jpg

Please note, the above is not the 11th commandment it works very well on many Giga Peer-to-Peer Networks, but your mileage might vary.

For real evaluation of the Network's performance use Qcheck.

http://www.ezlan.net/faq.html#transfer

 

[ScottMac]

And, the obligatory "make sure your cabling (in the wall, and patch cables) is up to snuff"

Bad cable (kinked, stretched, twisted, crushed, stepped-on, rolled-over, cat/dog-chewed, failed minimum bend radius ...) or poor termination (wrong pair order, too much untwisted, poor crimp, bad punch ...) will kill speed & throughput.

Also, as a toss-in, remember that GigE uses all four pair (both directions send & receive concurrently ... all four pair send and receive at the same time), so a bad pair (cabling or termination) will kill the entire GigE span and bring it down to 10/100Base operation (pair 2&3, pins 1&2, 3&6).