On Tue, 17 Dec 2002, Alain Knaff wrote:
There are several ways around this:
- Maybe your switch does understand IGMP, but this is just switched
off? Can you check what happens if you enable it (IGMP snooping)? N.B. Some 3com switches, and maybe others as well, do have a config option for IGMP snooping, but it is not actually implemented... (i.e. even if enabled, it doesn't work).
- Or if the above doesn't work, try disabling flow control in the
switch. With that config, the switch will just drop the packets that it cannot transmit on the 10Mb/s ports (but the 100 Mb/s ports still enjoy the complete transmission).
Unfortunately our switch is unmanaged, so I couldn't change the above.
- If that doesn't help either (or is unavailable), try unplugging all
devices that do not participate in the communication.
I did this and I got 94 Mbps for 2, 4 and 8 clients. So indeed, it seems to be a problem with the switch.
Not sure that this is the same problem as on 100Mbit/s. Indeed, as this technology is much more recent, most Gigabit switches (hopefully) should know how to correctly switch multicast traffic.
The switch is somewhat old (from the days when Gigabit Ethernet was still a new technology), but it should do the multicasting right. But it seems that the problem is not related to multicast (see below).
But maybe a different problem is occuring (but it might still be worth trying to disconnect from the Gigabit switch all devices that are unrelated to the transfer).
There are only 16 Gigabit Ethernet ports used on the switch (plus a management port).
Can you also retry this with the half-duplex flag, just in case?
I did so but it didn't help. What surprises me somewhat, is the fact the the performance is also very low for only 1 sender and 1 receiver. Here's what I tried:
On the receiver: node02:~/src/udpcast> time ./udp-receiver --file /dev/null --interface eth1 Udp-receiver 2001-12-31 UDP receiver for /dev/null at 172.25.1.102 172.25.1.102 on eth1 received message, cap=00000019 Connected as #0 to 172.25.1.101 172.25.1.102 Listening to multicast on 236.25.1.101 Press any key to start receiving data! bytes= 425 152 ( 0.42 Mbps) Cancelled by user 0.000u 0.010s 1:25.11 0.0% 0+0k 0+0io 138pf+0w
And on the sender: node01:~/src/udpcast> time ./udp-sender --file /dev/zero --half-duplex --interface eth1 Udp-sender 2001-12-31 172.25.1.101 Using mcast address 236.25.1.101 UDP sender for /dev/zero at 172.25.1.101 172.25.1.101 on eth1 Broadcasting control to 172.25.255.255 New connection from 172.25.1.102 (#0) 00000019 Ready. Press any key to start sending data. [RETURN] Starting transfer: 00000019 [CTRL-C about 80 seconds later] 0.000u 0.000s 1:22.93 0.0%mits=00+0k 0+0io 155pf+0we=0202 - 0
This should be a unicast transmission if I understand you right, but still I see much less than even 1 Mbps.
Regards, Felix