[ovs-discuss] Unexpected behavior of counters when installing new flow

Wed May 1 09:05:06 UTC 2013

Hi,

First to make sure there are no misunderstandings: the entries in the
switch are installed by the POX controller (as you have probably already
noticed).

For the test below (what you proposed) I added the /31 entry by hand to
make sure the issue is not due to some controller logic issue. And just a
remark: traffic is same as in the previous mail but at 1000 packet/s to
make it easier to interpret the values.

So starting traffic, let controller install entries and dump after a some
time:

NXST_FLOW reply (xid=0x4):
 cookie=0x3e8, duration=23.611s, table=0, n_packets=28, n_bytes=16520,
idle_age=0, icmp,nw_src=10.1.6.0/30,nw_dst=10.1.4.0/30 actions=output:1
 cookie=0x0, duration=52.033s, table=0, n_packets=31, n_bytes=1860,
idle_age=0, priority=65000,dl_dst=01:23:20:00:00:01,dl_type=0x88cc
actions=CONTROLLER:65535
 cookie=0x3eb, duration=18.558s, table=0, n_packets=0, n_bytes=0,
idle_age=18, arp,dl_src=00:25:90:64:f9:3e,dl_dst=90:e2:ba:00:9f:86
actions=output:2
 cookie=0x3ea, duration=18.598s, table=0, n_packets=1, n_bytes=60,
idle_age=18, arp,dl_src=90:e2:ba:00:9f:86,dl_dst=00:25:90:64:f9:3e
actions=output:1
 cookie=0x3e9, duration=23.606s, table=0, n_packets=23544,
n_bytes=25097904, idle_age=0, udp,nw_src=
10.1.4.0/30,nw_dst=10.1.6.0/30,tp_src=20,tp_dst=1000 actions=output:2

Kill traffic generation and dump:

NXST_FLOW reply (xid=0x4):
 cookie=0x3e8, duration=40.183s, table=0, n_packets=30, n_bytes=17700,
idle_age=15, icmp,nw_src=10.1.6.0/30,nw_dst=10.1.4.0/30 actions=output:1
 cookie=0x0, duration=68.605s, table=0, n_packets=41, n_bytes=2460,
idle_age=0, priority=65000,dl_dst=01:23:20:00:00:01,dl_type=0x88cc
actions=CONTROLLER:65535
 cookie=0x3eb, duration=35.13s, table=0, n_packets=1, n_bytes=60,
idle_age=10, arp,dl_src=00:25:90:64:f9:3e,dl_dst=90:e2:ba:00:9f:86
actions=output:2
 cookie=0x3ea, duration=35.17s, table=0, n_packets=2, n_bytes=120,
idle_age=10, arp,dl_src=90:e2:ba:00:9f:86,dl_dst=00:25:90:64:f9:3e
actions=output:1
 cookie=0x3e9, duration=40.178s, table=0, n_packets=*25049, n_bytes=26702234
*, idle_age=15, udp,nw_src=
10.1.4.0/30,nw_dst=10.1.6.0/30,tp_src=20,tp_dst=1000 actions=output:2

Starting traffic again and dump:

 cookie=0x3e8, duration=64.755s, table=0, n_packets=55, n_bytes=32450,
idle_age=0, icmp,nw_src=10.1.6.0/30,nw_dst=10.1.4.0/30 actions=output:1
 cookie=0x0, duration=93.177s, table=0, n_packets=54, n_bytes=3240,
idle_age=3, priority=65000,dl_dst=01:23:20:00:00:01,dl_type=0x88cc
actions=CONTROLLER:65535
 cookie=0x3eb, duration=59.702s, table=0, n_packets=3, n_bytes=180,
idle_age=9, arp,dl_src=00:25:90:64:f9:3e,dl_dst=90:e2:ba:00:9f:86
actions=output:2
 cookie=0x3ea, duration=59.742s, table=0, n_packets=4, n_bytes=240,
idle_age=9, arp,dl_src=90:e2:ba:00:9f:86,dl_dst=00:25:90:64:f9:3e
actions=output:1
 cookie=0x3e9, duration=64.75s, table=0, n_packets=44305, n_bytes=47229130,
idle_age=0, udp,nw_src=10.1.4.0/30,nw_dst=10.1.6.0/30,tp_src=20,tp_dst=1000actions=output:2

Adding entry by hand (sudo ovs-ofctl add-flow br0
cookie=0x3e8,table=0,udp,nw_src=
10.1.4.0/31,nw_dst=10.1.6.2/31,tp_src=20,tp_dst=1000,priority=65100,actions=output:2)
and dump:

NXST_FLOW reply (xid=0x4):
 cookie=0x3e8, duration=1.584s, table=0, n_packets=38256, n_bytes=40780896,
idle_age=0, priority=65100,udp,nw_src=
10.1.4.0/31,nw_dst=10.1.6.2/31,tp_src=20,tp_dst=1000 actions=output:2
 cookie=0x3e8, duration=83.559s, table=0, n_packets=74, n_bytes=43660,
idle_age=0, icmp,nw_src=10.1.6.0/30,nw_dst=10.1.4.0/30 actions=output:1
 cookie=0x0, duration=111.981s, table=0, n_packets=67, n_bytes=4020,
idle_age=0, priority=65000,dl_dst=01:23:20:00:00:01,dl_type=0x88cc
actions=CONTROLLER:65535
 cookie=0x3eb, duration=78.506s, table=0, n_packets=4, n_bytes=240,
idle_age=3, arp,dl_src=00:25:90:64:f9:3e,dl_dst=90:e2:ba:00:9f:86
actions=output:2
 cookie=0x3ea, duration=78.546s, table=0, n_packets=5, n_bytes=300,
idle_age=3, arp,dl_src=90:e2:ba:00:9f:86,dl_dst=00:25:90:64:f9:3e
actions=output:1
 cookie=0x3e9, duration=83.554s, table=0,* n_packets=25049, n_bytes=26702234
*, idle_age=2, udp,nw_src=
10.1.4.0/30,nw_dst=10.1.6.0/30,tp_src=20,tp_dst=1000 actions=output:2

So indeed, it seems to return to the values when the flow was idle.

Does this help?

Kind regards,

Tim

2013/5/1 Ben Pfaff <blp at nicira.com>

> On Tue, Apr 30, 2013 at 12:49:26PM +0200, Tmusic wrote:
> > Let me post some more debug information then:
>
> [...]
>
> > Does this provides more useful information?
>
> It gets me past the "I don't really believe this, it must be some
> misunderstanding" hurdle ;-)
>
> Are you willing to do a few experiments?  Here is one idea:
>
> 1. Start your stream and add the initial flow to the flow table (in
>    whatever order you like).  Let it run for a while, a few seconds at
>    least.
>
> 2. Dump stats with "ovs-ofctl dump-flows".
>
> 3. Stop your stream and "sleep 5" (or just wait 5 or more seconds
>    patiently).
>
> 4. Dump stats with "ovs-ofctl dump-flows".
>
> 5. Restart your stream.  Let it run for a while, a few seconds at least.
>
> 6. Add your higher-priority flow to the flow table.  Let the stream run
>    for a while, a few seconds at least.
>
> 7. Dump stats with "ovs-ofctl dump-flows".
>
> The question I'm trying to answer is whether the low-priority flow's
> stats drop to zero in step 7, or to the values seen in step 2, or
> something else entirely.
>
> Thanks,
>
> Ben.
>
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