Re: determining speed issues

<rhltechie@xxxxxxxxx> wrote in message
news:1177689694.092437.191040@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Hi All,

I fear I have speed issues in my network and I have started the chore
of looking to see if my suspicions are correct. I am using iperf
between my desktop and several servers. I have a 4507R with all
gigabit interface cards as the hub of my network. Connected via a 2gb
etherchannel are two stacked gig e 3750 switches onto which all of my
servers connect. What I have seen so far is that when i do tests
originating from my desktop to different servers, I am seeing roughly
83% of the gig e link used. Coming back though, I am consistently
seeing much lower speeds, probably 40% of the link. Below are some
tests I have done:

from my desktop to our exchange server:

E:\temp>iperf.exe -c <ex server address>
------------------------------------------------------------
Client connecting to <ex server address>, TCP port 5001
TCP window size: 63.0 KByte (default)
------------------------------------------------------------
[108] local <desktop address> port 51286 connected with <ex server
address> port 5001
[ ID] Interval Transfer Bandwidth
[108] 0.0-10.0 sec 969 MBytes 813 Mbits/sec


from a linux server to exchange server:

nagios# iperf -c <ex server address>
------------------------------------------------------------
Client connecting to 192.168.20.34, TCP port 5001
TCP window size: 126.0 KByte (default)
------------------------------------------------------------
[ 3] local <local system ip address> port 56182 connected with <ex
server address>port 5001
[ 3] 0.0-10.0 sec 1020 MBytes 892 Mbits/sec


from the exchange server to my desktop:

C:\Temp>iperf.exe -c <my desktop address> -w 63k
------------------------------------------------------------
Client connecting to <my desktop address>, TCP port 5001
TCP window size: 63.0 KByte
------------------------------------------------------------
[1908] local <ex local address> port 19240 connected with <my desktop
address> port 5001
[ ID] Interval Transfer Bandwidth
[1908] 0.0-10.0 sec 584 MBytes 489 Mbits/sec



Am I interpreting this info correctly? If so, where should I start in
trying to figure out what may be going on?

it could be the PC chokes on input

but since most networks have doiminant traffic flow from servers to clients,
maybe you have contending server flows thru the trunk from the server?

From other networks i would expect the Etherchannel to act as a bottleneck
all on it own if you have a reasonable number of servers, but it could be
worse than 2 Gbps depending on where it is plugged into the 4507.

some GigE blades in a 4500 are heavily contended internally since each blade
only gets 6 Gbps to the Sup (and even then doesnt share it all that evenly).

TIA,

R
--
Regards

stephen_hope@xxxxxxxxxxxx - replace xyz with ntl


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