Howdy!
Vasanthy Kolluri (vkolluri) je dne 21/03/11 19:49 napisal-a:
I have two iperf clients sending UDP packets to a iperf server. Once
the test is completed, the Server side results for only one of the
streams is reported both on the client and server.
Iperf client:
/# iperf -c 10.0.50.100 -B 10.0.50.1 -u -b1G -t100 &/
/# iperf -c 10.0.50.100 -B 10.0.50.2 -u -b1G -t100 &/
/ /
/[ ID] Interval Transfer Bandwidth/
/[ 3] 0.0-100.0 sec 9.38 GBytes 805 Mbits/sec/
/[ 3] Sent 6848733 datagrams/
/[ ID] Interval Transfer Bandwidth/
/[ 3] 0.0-100.0 sec 9.36 GBytes 804 Mbits/sec/
/[ 3] Sent 6837468 datagrams/
/[ 3] Server Report:/
/[ 3] 0.0-100.0 sec 5.02 GBytes 431 Mbits/sec 0.010 ms
3168363/6837467 (46%)/
/[ 3] 0.0-100.0 sec 18 datagrams received out-of-order/
/[ 3] *WARNING: did not receive ack of last datagram after 10 tries.*/
When doing UDP tests with requested bandwidth significantly hingher that
bottleneck permits last packets can get either delayed by too much or
dropped (most probably the former). Either way server doesn't send
report to client quickly enough for client to catch it before it exits.
This mostly doesn't happen when requested bandwidth is within link
capacity or when testing TCP (with its flow control).
In your case the limiting factor can well be the first leg (NIC of the
client machine) as you're requesting two times 1Gbps. The achieved
throughput seems to indicate you've really got some kind of 2Gbps link
out of client machine (achieved throughput is 805+804=1609 Mbps). Still
after 100 seconds TX buffer of your IP stack will be full and that
causes delay - how much depend on the size of buffer. Thre is some 1Gbps
bottleneck somewhere between client and server as server seems to get
slightly less than half of packets. Delay and dropped packets mean last
packets are not acked by server (bearing throughput report) to client.
Seems like last packets actually got dropped as server did not notice
that client was trying to close the connection.
If you want to get at least some statistics on server side, you could
set server for periodic reporting using /-i <interval>/ ... it won't
help to get report through client though.
--
Peace!
Mkx
-- perl -e 'print $i=pack(c5,(41*2),sqrt(7056),(unpack(c,H)-2),oct(115),10);'
-- echo 16i[q]sa[ln0=aln100%Pln100/snlbx]sbA0D4D465452snlb xq | dc
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