Hello,
Some things to add to this, after more investigations:
I am using the following command to rate-limit the traffic per port:
ovs-vsctl -- set port s1-eth2 qos=@newqos -- --id=@newqos create qos
type=linux-htb other-config:max-rate=1000000 queues:0=@newqueue --
--id=@newqueue create queue other-config:min-rate=1000000
other-config:max-rate=1000000
This will limit the OVS s1-eth2 port to 1mbps. However I push more traffic
through the switch, resulting in dropped packets.
Using dpctl I get:
root@mininet-vm:~# sudo ovs-dpctl show -s
system@s1:
lookups: hit:1272890 missed:31 lost:0
flows: 0
port 0: s1 (internal)
RX packets:0 errors:0 dropped:0 overruns:0 frame:0
TX packets:11 errors:0 dropped:0 aborted:0 carrier:0
collisions:0
RX bytes:0 TX bytes:798
port 1: s1-eth1
RX packets:1272895 errors:0 dropped:0 overruns:0 frame:0
TX packets:50 errors:0 dropped:0 aborted:0 carrier:0
collisions:0
RX bytes:1326329437 (1.2 GiB) TX bytes:3419 (3.3 KiB)
port 2: s1-eth2
RX packets:26 errors:0 dropped:2 overruns:0 frame:0
TX packets:1272919 errors:0 dropped:0 aborted:0 carrier:0
collisions:0
RX bytes:1859 (1.8 KiB) TX bytes:1326330997 (1.2 GiB)
Using tc utility I get:
root@mininet-vm:~# tc -s -p qdisc show dev s1-eth2
qdisc htb 1: root refcnt 2 r2q 10 default 1 direct_packets_stat 0
Sent 3545792 bytes 3430 pkt (dropped 1269476, overlimits 1278520 requeues 0)
backlog 0b 0p requeues 0
The tc reports 1269476 dropped packets for port s1-eth2, which is according to
the results I get from the traffic generator.
I don't understand why the dpctl does not report the same statistics as the tc
utility, per port?
The statistics that I get with dpctl are the ones reported through Openflow
port statistics request and they are not what I expect.
Thanks!
cosmin
-----Original Message-----
From: Cosmin Marius Caba
Sent: 7. marts 2014 08:09
To: 'Justin Pettit'
Cc: [email protected]
Subject: RE: [ovs-discuss] "lost" counter in the ovs-dpctl
Thanks for the reply. I should've checked the man page first.
I am working with Mininet and Floodlight. I'm trying to dimension a network
with limited capacity to compare two routing algorithms, with respect to packet
loss.
I am using D-ITG traffic generator to put traffic in the network.
I would like to get statistics in the controller about the packet loss per
port, using the OF statistics request message.
Now I'm using a very simple scenario with one OVS and two hosts (scenario
created using the mininet API).
UDP flows are sent from one host to the other and the traffic generator reports
significant packet loss because the links have only 10mbps capacity in mininet.
I was expecting to find this packet loss on the Tx ports of the OVS. I
understand now that the packets may be dropped somewhere outside of OVS (maybe
on the virtual links create by mininet).
How should I dimension a network of OVSs (manually, not through mininet) such
that the Tx port capacity (outgoing links) is limited, so I can get the packet
loss on the port and not on other parts of the software emulation?
Regards,
Cosmin
-----Original Message-----
From: Justin Pettit [mailto:[email protected]]
Sent: 6. marts 2014 19:16
To: Cosmin Marius Caba
Cc: [email protected]
Subject: Re: [ovs-discuss] "lost" counter in the ovs-dpctl
On Mar 6, 2014, at 5:56 AM, Cosmin Marius Caba <[email protected]> wrote:
> What does the lookups entry mean? More specifically the lost counter?
From the ovs-dpctl man page:
The "lookups" row displays three stats related to flow lookup
triggered by processing incoming packets in the datapath. "hit"
displays number of packets matches existing flows. "missed" dis‐
plays the number of packets not matching any existing flow and
require user space processing. "lost" displays number of pack‐
ets destined for user space process but subsequently dropped
before reaching userspace. The sum of "hit" and "miss" equals to
the total number of packets datapath processed.
> Is the lost counter in the lookups entry related to the number of dropped
> packets that I see at the end-points of a traffic low?
Most likely. There are other places in the network where packets can get lost,
too.
> If yes, then why there are no dropped packets on any of the ports?
Which ports? It sounds like you are experiencing packet loss.
By the way, starting in OVS 1.11, the number of "lost" packets in most
deployments should be substantially reduced.
--Justin
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