Pkafkas
asked on
What is considered good or bad bandwidth for a GB LAN?
I ran the network tool 'IPerf" on 2 PC's that are connected by several GB Switches. The results are pretty close every time I ran the test, please see below
G:\Downloads\Iperf\From_Fr
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Client connecting to XXX.XXX.XXX.151, TCP port 5001
TCP window size: 64.0 KByte (default)
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[ 3] local XXX.XXX.XXX.151 port 64114 connected with XXX.XXX.XXX.151 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 719 MBytes 603 Mbits/sec
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My question is this acceptable for a GB switch network? I suppose if you take 603 and divide into 719 that is 83%; but, I have no frame of reference. I would think that the power of the computers make a difference as well; but, can someone explain to me:
Question1: What is considered good bandwidth results for a GB LAN connection?
Question2: What is considered bad babdwidth results for a GB LAN connection?
Question3: How can I make a definitive test using Iperf? or any other utility?
G:\Downloads\Iperf\From_Fr
--------------------------
Client connecting to XXX.XXX.XXX.151, TCP port 5001
TCP window size: 64.0 KByte (default)
--------------------------
[ 3] local XXX.XXX.XXX.151 port 64114 connected with XXX.XXX.XXX.151 port 5001
[ ID] Interval Transfer Bandwidth
[ 3] 0.0-10.0 sec 719 MBytes 603 Mbits/sec
--------------------------
My question is this acceptable for a GB switch network? I suppose if you take 603 and divide into 719 that is 83%; but, I have no frame of reference. I would think that the power of the computers make a difference as well; but, can someone explain to me:
Question1: What is considered good bandwidth results for a GB LAN connection?
Question2: What is considered bad babdwidth results for a GB LAN connection?
Question3: How can I make a definitive test using Iperf? or any other utility?
SOLUTION
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ASKER CERTIFIED SOLUTION
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ASKER
Thank you everyone. My next question was going to be how to interpret the results from the iperf test. But noci took care of that.
How may I increase the size of the "window" to 256KB in the iperf test?
How may I increase the size of the "window" to 256KB in the iperf test?
-w option?
I tried here with different window sizes. Too large a window doesn;t help. 128KB gave best results (on my LAN).
One switch between 2 nodes. (-w 128K)
[ 4] 1.00-2.00 sec 112 MBytes 940 Mbits/sec 0 88.4 KBytes
-w 32K
[ 4] 3.00-4.00 sec 66.6 MBytes 558 Mbits/sec 0 29.9 KBytes
(Last column was the effective window size when ack was received).
with -w 256K there were too many retries, so some tunning on the kernel level might be required on my network.
also try udp in stead of tcp connection. Be sure to specify your want a 1Gpbs bandbidth though.
(UDP has no overhead like ack going back and forth)
I tried here with different window sizes. Too large a window doesn;t help. 128KB gave best results (on my LAN).
One switch between 2 nodes. (-w 128K)
[ 4] 1.00-2.00 sec 112 MBytes 940 Mbits/sec 0 88.4 KBytes
-w 32K
[ 4] 3.00-4.00 sec 66.6 MBytes 558 Mbits/sec 0 29.9 KBytes
(Last column was the effective window size when ack was received).
with -w 256K there were too many retries, so some tunning on the kernel level might be required on my network.
also try udp in stead of tcp connection. Be sure to specify your want a 1Gpbs bandbidth though.
(UDP has no overhead like ack going back and forth)
ASKER
It was stated that "603Mbps is not too shabby. "
May I ask what is considered bad? Is it less than 50%, so less 500Mbps?
May I ask what is considered bad? Is it less than 50%, so less 500Mbps?
SOLUTION
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@pedrag:
iperf doesn't use a file transfer. So it is a correct statement / observation, albeit not relevant.
About 603Mbps being not too shabby meaning that there is room for improvement, but it might be the best attainable under current circumstances.
Q is how many switches in between the nodes. If there is fragmentation of packets that causes a big overhead...
I forgot to mention the receiving statistics for the UDP test, which come down to:...
[ 5] 2.00-3.00 sec 6.24 MBytes 52.4 Mbits/sec 0.074 ms 14181/14980 (95%)
so huge packets loss on UDP packet re-assembly (Those are 8KB packets in MTU 1500 frames). doesn't happen for TCP like this, unless the MTU is not the same along the path.
iperf doesn't use a file transfer. So it is a correct statement / observation, albeit not relevant.
About 603Mbps being not too shabby meaning that there is room for improvement, but it might be the best attainable under current circumstances.
Q is how many switches in between the nodes. If there is fragmentation of packets that causes a big overhead...
I forgot to mention the receiving statistics for the UDP test, which come down to:...
[ 5] 2.00-3.00 sec 6.24 MBytes 52.4 Mbits/sec 0.074 ms 14181/14980 (95%)
so huge packets loss on UDP packet re-assembly (Those are 8KB packets in MTU 1500 frames). doesn't happen for TCP like this, unless the MTU is not the same along the path.
ASKER
There were 2 64 - bit PC's connected through 2 x GB Ethernet switches.
Both - PCs have non-ssd drives.
I think that there most likely is not a problem with the ethernet; but, how can I be sure.
Both - PCs have non-ssd drives.
I think that there most likely is not a problem with the ethernet; but, how can I be sure.
traceroute?
ping times?
Those have been mentioned as "you need to determine latency as well"
ping times?
Those have been mentioned as "you need to determine latency as well"
You can't make a "definitive test" for all circumstances. You can check other methods and see if you're getting what you expect.