[ovs-discuss] packets getting dropped at egress

[Joe Stringer]

Have you tried decreasing the MTU of portA such that packets are
encapsulated they're <=1500B?

On 23 July 2015 at 08:19, Dave Waters <davewaters1970 at gmail.com> wrote:
> Its not. But how do i ensure that my packet does not get dropped somewhere
> downstream, since i have now increased it beyond the original value?
>
> On Thu, Jul 23, 2015 at 7:49 PM, gowrishankar
> <gowrishankar.m at linux.vnet.ibm.com> wrote:
>>
>> On Thursday 23 July 2015 04:16 AM, Dave Waters wrote:
>>>
>>> Hi,
>>>
>>> I have two ports in my OVS bridge. I receive packets from one port
>>> (portA) and i send them out of the other (portB). When i send out the
>>> packets, they are VXLAN tunneled to the other end.
>>>
>>> Now, the default MTU of all ports (including the bridge port) is 1500 in
>>> my setup.
>>>
>>> The issue is that when i get a 1500 byte packet on portA, i try to push
>>> it out on portB after slapping on the VXLAN headers. This results in a
>>> packet size thats greater than what portB can handle, and hence the packets
>>> are dropped.
>>>
>>
>> Is increasing MTU of portB to 1550 (to accommodate additional 50 bytes
>> when no vlan taged) a constraint in your setup ?
>>
>>
>>> I know that OVS does not handle IP fragmentation/reassembly, so how do we
>>> deal with this situation? I dont think we can rely on path MTU discovery
>>> since not all applications do PMTU before spewing out packets. Any ideas,
>>> anybody?
>>>
>>> Warm regards,
>>> Dave
>>>
>>
>> --
>> Regards,
>> Gowrishankar M
>>
>
>
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