Multicast testing
- To: iperf-users --at-- dast.nlanr.net
- Subject: Multicast testing
- From: Mike Lancaster <mikelancuk --at-- yahoo.co.uk>
- Date: Thu, 30 Nov 2006 16:51:37 +0000 (GMT)
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I'm testing that multicast sent from one machine is being forwarded to another subnet. Could anyone explain to me what is happening and why?
I start an iperf server on machine A which is on subnet A.
/tmp/iperf_rhel4 -s -u -B 231.1.84.21 -i 1 -p 26240
Output is;
------------------------------------------------------------
Server listening on UDP port 26240
Binding to local address 231.1.84.21
Joining multicast group 231.1.84.21
Receiving 1470 byte datagrams
UDP buffer size: 256 KByte (default)
------------------------------------------------------------
I start a client on machine B which is on subnet B
/tmp/iperf_rhel4 -c 231.1.84.21 -u -T 32 -t 9999 -i1 -p 26240
Output is;
------------------------------------------------------------
Client connecting to 231.1.84.21, UDP port 26240
Sending 1470 byte datagrams
Setting multicast TTL to 32
UDP buffer size: 108 KByte (default)
------------------------------------------------------------
[ 3] local <machine A> port 18218 connected with 231.1.84.21 port 26240
[ 3] 0.0- 1.0 sec 129 KBytes 1.06 Mbits/sec
[ 3] 1.0- 2.0 sec 128 KBytes 1.05 Mbits/sec
[ 3] 2.0- 3.0 sec 128 KBytes 1.05 Mbits/sec
[ 3] 3.0- 4.0 sec 128 KBytes 1.05 Mbits/sec
[ 3] 4.0- 5.0 sec 128 KBytes 1.05 Mbits/sec
Nothing is received on the server on machine A
If I then run tcpdump in another session on machine A (tcpdump host 231.1.84.21) I get output in the server window;
[ 3] local 231.1.84.21 port 26240 connected with <machine A> port 18224
[ 3] 0.0- 1.0 sec 128 KBytes 1.05 Mbits/sec 0.739 ms 254/ 343 (74%)
[ 3] 1.0- 2.0 sec 128 KBytes 1.05 Mbits/sec 0.550 ms 0/ 89 (0%)
[ 3] 2.0- 3.0 sec 128 KBytes 1.05 Mbits/sec 0.608 ms 0/ 89 (0%)
[ 3] 3.0- 4.0 sec 129 KBytes 1.06 Mbits/sec 0.628 ms 0/ 90 (0%)
[ 3] 4.0- 5.0 sec 128 KBytes 1.05 Mbits/sec 0.632 ms 0/ 89 (0%)
[ 3] 0.0- 5.8 sec 742 KBytes 1.05 Mbits/sec 0.648 ms 254/ 771 (33%)
Does iperf not join the stream? Is this why I don't get output until tc
o do with tcpdump putting the network interface into promiscuous mode?
Thanks in advance for any help,
Mike
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