[ovs-discuss] dropped over-mtu packet:

[Jesse Gross]

It's likely due to the driver coalescing segments but not properly
setting up the metadata, which happened with some versions of the
Broadcom driver. You can look at the LRO and GRO settings on the NIC
as a temporary workaround.

On Mon, Dec 2, 2013 at 6:51 AM, kevin parker <kevin.parker092 at gmail.com> wrote:
> Thanks for the reply Philip,
>                                  You are right i have TSO
> (tcp-segmentation-offload: on) enabled on eth0 and eth1,but no other servers
> are
> showing this in dmesg.
>
> Also With TSO on,why ovs is dropping frames rather than fragmenting it.
>
> Regards,
> Kevin
>
> Hi,
>>
>>
>> seems that you have TSO enabled?
>> you can check the offloading features of your NIC with ethtool.
>>
>> Best,
>>
>> Philip
>>
>> Am 02.12.13 15:09, schrieb kevin parker:
>>
>>  Hi,
>>     I am confused with this in dmesg
>>     dmesg |grep "mtu"
>> [10674662.495400] openvswitch: xapi3: dropped over-mtu packet: 2853 > 1500
>> [10674662.495406] openvswitch: xapi3: dropped over-mtu packet: 2853 > 1500
>> [10674662.495411] openvswitch: xapi3: dropped over-mtu packet: 2853 > 1500
>> [10674662.495432] openvswitch: xapi3: dropped over-mtu packet: 4082 > 1500
>> [10674662.495435] openvswitch: xapi3: dropped over-mtu packet: 4082 > 1500
>> [10674662.495441] openvswitch: xapi3: dropped over-mtu packet: 4082 > 1500
>> [13413434.378976] openvswitch: xapi3: dropped over-mtu packet: 4082 > 1500
>> [13413434.378982] openvswitch: xapi3: dropped over-mtu packet: 4082 > 1500
>> [13413434.378989] openvswitch: xapi3: dropped over-mtu packet: 4082 > 1500
>> [13413434.379050] openvswitch: xapi3: dropped over-mtu packet: 2556 > 1500
>> [13413434.379054] openvswitch: xapi3: dropped over-mtu packet: 2556 > 1500
>> [13413434.379058] openvswitch: xapi3: dropped over-mtu packet: 2556 > 1500
>>
>> All interfaces are configured with MTU of 1500 (netstat -i )and on
>> physical switch also it is 1500.
>>
>> I dont understand why it is showing above in dmesg,can some one explain me
>> why something is trying to send Frames above 1500 and getting blocked by
>> ovs,even if no interface has an MTU of 1500 < .Is there any way to find out
>> what is trying to send frames larger than 1500.
>>
>> ovs-vsctl -V
>> ovs-vsctl (Open vSwitch) 1.4.2
>> Compiled Nov 23 2012 12:41:37
>>
>> ovs-dpctl show
>> system at xapi3:
>> lookups: hit:47665012972 missed:27317456871 lost:156544274
>> flows: 829
>> port 0: xapi3 (internal)
>> port 1: eth1
>> port 2: eth0
>> port 4: xapi4 (internal)
>> port 31: vif28.0
>> port 32: vif29.0
>> port 33: vif30.0
>>
>> ovs-vsctl list-ports xapi3
>> bond1
>>
>> ovs-appctl bond/show bond1
>> bond_mode: active-backup
>> bond-hash-basis: 0
>> updelay: 31000 ms
>> downdelay: 200 ms
>> lacp_negotiated: false
>>
>> slave eth1: enabled
>> active slave
>> may_enable: true
>>
>> slave eth0: enabled
>> may_enable: true
>>
>> Regards,
>> Kevin
>>
>>
>>
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>>
>>
>>
>> --
>> Philip Wette, M.Sc.             E-Mail: wette at mail.upb.de
>> University of Paderborn         Tel.:   05251 / 60-1716
>> Department of Computer Science
>> Computer Networks Group         http://wwwcs.upb.de/cs/ag-karl
>> Warburger Straße 100            Room:   O3.152
>> 33098 Paderborn
>>
>>
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>>
>
>
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