[ovs-discuss] OVS 2.8.1 changes the rates of data packets!

Dawood Sajjadi s.d.sajjadi at gmail.com
Wed Dec 13 23:19:16 UTC 2017


just as an update, I found out a way to solve my problem, but not sure how
it causes it! I was trying to do hop-by-hop routing over a wireless mesh
network bt setting eth_dst field (Re-writing of Destination MAC).  In my
prior configuration, I was not re-writing the eth_src field at each router,
but in the new one (as follows), I added it into the action section of my
rule (at the controller):

     "actions":[
        {
            "type":"SET_FIELD",
            "field": "eth_src",
            "value": "04:f0:21:11:3d:78"
        },
        {
            "type":"SET_FIELD",
            "field": "eth_dst",
            "value": "04:f0:21:11:3d:81"
        },
        {
            "type":"OUTPUT",
            "port": 2
        }
    ]

After applying the updated rule, the throughput problem is solved. However,
I don't understand how it affects the end-to-end throughput of flows over
the bridge/network. any comment?


On Sat, Dec 9, 2017 at 3:59 PM, Dawood Sajjadi <s.d.sajjadi at gmail.com>
wrote:

> I didn't make any conclusion. I just stated whatever I have experienced
> and as I mentioned before since by removing the wireless interfaces from
> the bridge, there is no rate limitation problem, then (at least) OVS plays
> a role in this problem. Ben: may I know what do you suggest to deal with
> this problem?
>
> On Fri, Dec 8, 2017 at 7:44 PM, Ben Pfaff <blp at ovn.org> wrote:
>
>> It seems like you're just jumping to conclusions here.  What have you
>> done to understand the situation?
>>
>> On Fri, Dec 08, 2017 at 05:59:57PM -0800, Dawood Sajjadi wrote:
>> > when I remove the wireless interfaces from the bridge, there is no
>> problem.
>> > However, as soon as adding the wireless interfaces to the bridge, the
>> > problem shows up. So, it seems OVS (at least) is a part of the problem.
>> >
>> > On Fri, Dec 8, 2017 at 5:55 PM, Ben Pfaff <blp at ovn.org> wrote:
>> >
>> > > On December 8, 2017 5:53:44 PM PST, Dawood Sajjadi <
>> s.d.sajjadi at gmail.com>
>> > > wrote:
>> > >>
>> > >> I created a bridge using OVS 2.8.1 in Ubuntu 14.04. The bridge
>> contains 4
>> > >> physical ports including one ethernet and three wireless ports. The
>> > >> ethernet port is connected to a laptop that generated dummy traffic
>> using
>> > >> Iperf. So, the ethernet port is used as the incoming port and the
>> generated
>> > >> traffic leaves the bridge through the wireless (as the outgoing)
>> ports. I
>> > >> used tcpdump to capture the traffic at the incoming and outgoing
>> ports of
>> > >> the bridge and I noticed that the volume of the outgoing traffic (at
>> the
>> > >> wireless ports) is by far lower than the amount of the incoming
>> traffic
>> > >> (from the ethernet port). It seems the OVS bridge drops/limits the
>> rate of
>> > >> outgoing packets. For instance, if the size of the captured traffic
>> using
>> > >> tcpdump at eth0 is 15 MB, the total size of the captured traffic on
>> > >> wireless ports is 3 MB!
>> > >>
>> > >> I didn't make any change in the default configuration of the OVS.
>> Also,
>> > >> to ensure that there is no predefined Queue/QoS policy at the
>> bridge, I
>> > >> used "ovs-vsctl --all destroy qos && ovs-vsctl --all destroy queue"
>> > >> command. However, the problem persists! Has anyone encountered such
>> an
>> > >> issue before? I really appreciate having your feedback. Thanks.
>> > >>
>> > >
>> > > OVS doesn't change data rates. You should try to figure out what's
>> going
>> > > on without making that assumption.
>> > >
>>
>
>
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