Iperf3: how to use SCTP with several interfaces

[Neestoor]

Hi, I am trying SCTP with iperf3. I have checked two different options, with
-P and --nstreams. In this case I had only one interface. First I used “iperf3
– c IPsrv -t 4 -i 2 –SCTP -P 2” to parallel several streams options with
results around 600Mbps for each connection. Then, I used “iperf3 – c IPsrv
-t 4 -i 2 –SCTP -nstreams 2” but in this case the results were very bad,
around 260 kbps and 0 kbps respectively. Do you know what it is going on?

In addition, I would like to try SCTP using simultaneously different
interfaces at the same host, with different IP address. How can I call iperf3 in order to
use these interfaces with SCTP under only one SCTP association? Do you have any
example?

Thanks in advance.

root@ubuntu:/home/cliente/Downloads# iperf3 -c 192.168.130.132 -t 4 -i 2 --sctp --nstreams 2
Connecting to host 192.168.130.132, port 5201
[ 5] local 192.168.130.131 port 45761 connected to 192.168.130.132 port 5201
[ ID] Interval Transfer Bitrate
[ 5] 0.00-2.00 sec 64.0 KBytes 262 Kbits/sec
[ 5] 2.00-4.00 sec 0.00 Bytes 0.00 bits/sec

---

[ ID] Interval Transfer Bitrate
[ 5] 0.00-4.00 sec 64.0 KBytes 131 Kbits/sec sender
[ 5] 0.00-4.00 sec 64.0 KBytes 131 Kbits/sec receiver

iperf Done.
root@ubuntu:/home/cliente/Downloads# iperf3 -c 192.168.130.132 -t 4 -i 2 --sctp -P 2
Connecting to host 192.168.130.132, port 5201
[ 5] local 192.168.130.131 port 45226 connected to 192.168.130.132 port 5201
[ 7] local 192.168.130.131 port 57767 connected to 192.168.130.132 port 5201
[ ID] Interval Transfer Bitrate
[ 5] 0.00-2.01 sec 167 MBytes 697 Mbits/sec
[ 7] 0.00-2.01 sec 164 MBytes 684 Mbits/sec
[SUM] 0.00-2.01 sec 331 MBytes 1.38 Gbits/sec

---

[ 5] 2.01-4.00 sec 169 MBytes 711 Mbits/sec
[ 7] 2.01-4.00 sec 168 MBytes 708 Mbits/sec
[SUM] 2.01-4.00 sec 337 MBytes 1.42 Gbits/sec

---

[ ID] Interval Transfer Bitrate
[ 5] 0.00-4.00 sec 336 MBytes 704 Mbits/sec sender
[ 5] 0.00-4.00 sec 336 MBytes 704 Mbits/sec receiver
[ 7] 0.00-4.00 sec 332 MBytes 696 Mbits/sec sender
[ 7] 0.00-4.00 sec 332 MBytes 696 Mbits/sec receiver
[SUM] 0.00-4.00 sec 668 MBytes 1.40 Gbits/sec sender
[SUM] 0.00-4.00 sec 668 MBytes 1.40 Gbits/sec receiver

iperf Done.

[bmah888]

I don't think iperf3 supports the multipathing functionality you're asking about. The SCTP support is pretty rudimentary and I don't think it gets used very much in general (we don't use this within ESnet at all). It's also possible that it's buggy and/or not-well-performing, which could explain the performance values you saw. (Another thought is that the kernel SCTP implementation might not be as well-performing as TCP.) Wish I had a better answer for you, but I think fixing these problems would take some investigation and/or development effort, probably by somebody other than ESnet.

[davidBar-On]

Regarding the specific issues raised (I can't help with the general issue of SCTP support):

1. Did you check the server output when --nstreams 2 was set? My guess is that the 64K is the buffer size of the client machine, and that no message was received by the server. If this is the case, maybe there is a problem in the SCTP settings in the client and/or server machines.
2. Regarding "using simultaneously different interfaces at the same host" - can the --xbind option help? Note that this option can repeat several times in the command line.