I'm setting up some experiments to test firewall performance on a gigabit testbed,
however I'm having trouble with silent periods in traffic leaving the linux router
of approx 1ms.
Kernel: 2.4.20 with sk98lin drivers, NF enabled but no modules loaded
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
10.0.44.0 * 255.255.255.0 U 40 0 0 eth1
10.0.42.0 * 255.255.255.0 U 40 0 0 eth0
default rap42 0.0.0.0 UG 40 0 0 eth0
HW: single AMD Athlon(TM) MP 2000+, and two SK-9821 V2.0 nic's
Traffic is generated using a tool similar to tcpreplay.
Example (mangled ip's):
input to the linux router: 1057074914.032191 19.28.139.88.8030 > 132.115.188.35.1293: P ... 1057074914.032192 100.19.181.123.80 > 132.115.157.52.3284: . ... 1057074914.032193 100.172.61.210.6346 > 132.98.243.140.1661: S ... 1057074914.032383 19.28.139.88.8030 > 132.115.188.35.1293: . ...
output from the linux router:
1057074914.032406 19.28.139.88.8030 > 132.115.188.35.1293: P ...
1057074914.032407 100.19.181.123.80 > 132.115.157.52.3284: . ...
1057074914.120901 100.172.61.210.6346 > 132.98.243.140.1661: S ...
^^^^
1057074914.121328 19.28.139.88.8030 > 132.115.188.35.1293: . ...Traces were taken on the router itself - however problem remains when monitoring ports using a switch. Furthermore, I've found that using identical ip addressses in the generated traffic makes the delay go away, but thats not really an option.
Is this normal behavior? solutions?
Cheers Mikkel
more details on http://www.cs.auc.dk/~mixxel/silent
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