Why is iperf reporting < 400 Mbit/sec for a gigabit network?

[sofakng]

I'm trying to test my network speed and I'm using iperf (because I don't know of any other tools) and I'm getting between 200 and 300 megabits per second every way I've tested.

Example:

Windows 7 to Router
Windows 7 to Windows Server 2008 R2
Windows Server 2008 R2 to Router

Hardware:

Windows 7 (Marvell NICs)
Windows Server 2008 R2 (Intel, dual-port, PCIe)
Router (Intel, on-board [Supermicro motherboard])
Switch: Netgear GS108T (managed switch, 8-port gigabit)

I can understand if the Marvell NIC in my Windows 7 machine is garbage but why am I only showing 200-300 between the server and router, both which have Intel chips?

Example from last my last run:

------------------------------------------------------------
Client connecting to 192.168.0.1, TCP port 5001
TCP window size: 8.00 KByte (default)
------------------------------------------------------------
[148] local 192.168.0.198 port 54279 connected with 192.168.0.1 port 5001
[ ID] Interval Transfer Bandwidth
[148] 0.0-10.2 sec 153 MBytes 126 Mbits/sec

 

[yinan]

[148] 0.0-10.2 sec 153 MBytes 126 Mbits/sec

If that is 153 MB per second then that is really good because you are getting your B's confused.

 

[DnetMHZ]

TCP window size: 8.00 KByte (default)

I'll defer to the experts here but I think you'd want to bump this up, no?

 

[Crusty]

[148] 0.0-10.2 sec 153 MBytes 126 Mbits/sec

If that is 153 MB per second then that is really good because you are getting your B's confused.

If that is 153MB/s then he's using 10gbe because gigabit can not transfer that fast. 153MB/s * 8 bits/1 byte = 1224Mb/s

I'm guessing it was, 10.2s to transfer 153MB which is equal to ~ 120Mb/s

As for the OP's problem, what kind of cables are you using and where did you get them?

 

[sofakng]

I've just run another test at 64 KB between my two Intel NICs:

------------------------------------------------------------
Client connecting to 192.168.0.1, TCP port 5001
TCP window size: 64.0 KByte
------------------------------------------------------------
[172] local 192.168.0.50 port 50922 connected with 192.168.0.1 port 5001
[ ID] Interval Transfer Bandwidth
[172] 0.0-10.1 sec 256 MBytes 212 Mbits/sec

It's saying that in 10 seconds it transferred 256 megabytes which is 212 megaBITs/sec or 26.5 megabytes/sec which is horrible...

 

[Emulex]

try a udp test to measure packet loss. then you can start figuring out if its the rate of output or rate of input (or loss in between) that is causing the issue.

 

[sofakng]

Here's a UDP test:

------------------------------------------------------------
Client connecting to 192.168.0.1, UDP port 5002
Sending 1470 byte datagrams
UDP buffer size: 64.0 KByte
------------------------------------------------------------
[148] local 192.168.0.198 port 51608 connected with 192.168.0.1 port 5002
[ ID] Interval       Transfer     Bandwidth
[148]  0.0-10.0 sec  1.25 MBytes  1.05 Mbits/sec
[148] Server Report:
[148]  0.0-10.0 sec  1.25 MBytes  1.05 Mbits/sec  0.029 ms    0/  893 (0%)
[148] Sent 893 datagrams

 

[EricMartello]

I can understand if the Marvell NIC in my Windows 7 machine is garbage but why am I only showing 200-300 between the server and router, both which have Intel chips?

200-300 Mbps is 25 to 38 MB/s...what kind of hard drive...if your hard drives are not slow, how is the CPU utilization?

What kind of NIC settings are you using. Do you have jumbo frames disabled? Did you disable flow control? Are you using the manufacturer's drivers or did you try getting drivers from Windows Update (which sometimes work better).

Does your router have any type of traffic shaping enabled, or are you running any type of software firewall on the computer which may be interfering?

Those are some things that may be affecting your performance.

 

[Emulex]

oh i figured the dude was using a switch - routers can firewall/qos and reduce throught. go spend $10 on a 5-port gigabit switch man. separate route/switch for sure. jumbo frames are a no-no on an internet facing port. keep jumbo for vmotion/iscsi/fcoe/aoe type traffic.