On 6/23/06, Johannes Deleu <Johannes.Deleu@xxxxxxxxxxxxxx> wrote:
Hi,
for a project, we're interested in using DCCP. As such, I did some
performance measurements with the latest version of the DCCP
implementation. To my opinion, they are not really what I expected.
Could you give some ideas or maybe some information about the current
status of the implementation (e.g. is packet loss detection planned for
implementation, when ?) ?
Packet loss has been implemented and is working for me. What is your
test environment? I am using netem on a router between two boxes.
Results of similar tests are also interesting to see if they compare.
For the tests, I used an impairment node (based on linux, which
introduced some packet loss).
Measurements where performed with the patched iperf on linux-2.6.16.20
and I came to the following table:
TCP DCCP-CCID3 (Send/Recv)
No drop 94 Mbps 93.3 Mbps 93.2 Mbps
Drop 1% 83.4 Mbps 93.3 Mbps 92.3 Mbps
Drop 5% 16.6 Mbps 93.3 Mbps 88.6 Mbps
Drop 10% 3.25 Mbps 93.3 Mbps 83.9 Mbps
The transmitter does not detect the packet loss and doesnt slow down,
instead it keeps sending <CCID option 192 4294967295>.
As CCID3 is TFRC, I expected similar results for TCP and DCCP-CCID3.
When i tried out linux-2.6.17.1 (no packet drop) the receiver seems to
stop sending feedback packets after a while and the transmitter slows
down. The receiving process doesnt receive any data (recv doesnt return).
[ 3] local 10.0.1.3 port 3743 connected with 10.0.1.1 port 5001
[ 3] 0.0- 1.0 sec 11.0 MBytes 92.5 Mbits/sec
[ 3] 1.0- 2.0 sec 10.9 MBytes 91.6 Mbits/sec
[ 3] 2.0- 3.0 sec 10.9 MBytes 91.6 Mbits/sec
[ 3] 3.0- 4.0 sec 10.9 MBytes 91.6 Mbits/sec
[ 3] 4.0- 5.0 sec 10.9 MBytes 91.6 Mbits/sec
[ 3] 5.0- 6.0 sec 10.9 MBytes 91.6 Mbits/sec
[ 3] 6.0- 7.0 sec 6.86 MBytes 57.5 Mbits/sec
[ 3] 7.0- 8.0 sec 194 KBytes 1.59 Mbits/sec
[ 3] 8.0- 9.0 sec 100 KBytes 819 Kbits/sec
[ 3] 9.0-10.0 sec 100 KBytes 819 Kbits/sec
[ 3] 10.0-11.0 sec 100 KBytes 819 Kbits/sec
[ 3] 11.0-12.0 sec 100 KBytes 819 Kbits/sec
[ 3] 12.0-13.0 sec 100 KBytes 819 Kbits/sec
There are a few issues still with DCCP at the moment (which is why it
is marked experimental). Keep supplying us data/info and we will see
what we will do. Nobody is working fulltime on this code so it can
take a while to fix - feel free to help though!
One note - when using CCID3 have you turned off ackvecs via the sysctl
as that is really for CCID2... It's probably something we should do in
the code actually.
Ian
--
Ian McDonald
Web: http://wand.net.nz/~iam4
Blog: http://imcdnzl.blogspot.com
WAND Network Research Group
Department of Computer Science
University of Waikato
New Zealand
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