I have done a few tests with delay / loss, in particular the instances
specified on
http://linux-net.osdl.org/index.php/DCCP_Testing#Regression_testing
Without delay/loss, I get line speed (92.0 Mbps from e100 to e1000, 95.0 Mbps
from e1000 to e100).
This was for t=10 seconds; the following test runs were all done for t = 20
seconds.
1) Light Loss (40 msec RTT, 1 %loss)
------------------------------------
* calculated value: 3.20 Mbps (s = 1424)
* Test runs: 3.21 Mbps, 3.19 Mbps, 3.18 Mbps
2) Heavy Loss (150 msec RTT, 10 %loss)
--------------------------------------
* calculated value: 134.34 Kbps
* test runs:
(a) with a FIFO length of 1000 at the bridge
209 Kbps, 186 Kbps, 182 Kbps
(b) with a FIFO length of 10,000 at the bridge
197 Kbps, 176 Kbps, 134 Kbps
(I am using different FIFO length since I know from experience that otherwise
the bridge
can also incur loss.)
==> I actually have a question here, regarding the variability.
I am setting the same loss in either direction, i.e. on the bridge I do
tc qdisc add dev eth0 root netem delay 75ms loss 10%
tc qdisc add dev eth1 root netem delay 75ms loss 10%
I note that on
http://linux-net.osdl.org/index.php/DCCP_Testing#Network_emulation_setup
different loss values for forward/return are used. Has anyone further
experience with this?
I wonder if feedback loss has heavier implications than forward loss?
Script I used:
http://www.erg.abdn.ac.uk/users/gerrit/dccp/testing_dccp/tfrc_test.tc
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