[ovs-discuss] trace route for vxlan overlay network

Jesse Gross jesse at kernel.org
Mon Jan 4 19:44:42 UTC 2016


BFD is built into OVS, not an external application. It should not be
hard to find out how it works by grepping the OVS source code.

On Sun, Dec 27, 2015 at 2:40 AM, Avi Cohen <avi.cohen at huawei.com> wrote:
> Jesse,
> Thanks for your immediate response.
> Can u refer me to a sample applications/architecture  (bfd?)  injecting/receiving  packet to/from  OVS
> Regards  avi
>
> -----Original Message-----
> From: Jesse Gross [mailto:jesse at kernel.org]
> Sent: Wednesday, 23 December, 2015 2:46 AM
> To: Avi Cohen
> Cc: discuss at openvswitch.org
> Subject: Re: [ovs-discuss] trace route for vxlan overlay network
>
> On Tue, Dec 22, 2015 at 7:53 AM, Avi Cohen <avi.cohen at huawei.com> wrote:
>> Hello all
>>
>> I saw in
>> https://www.mail-archive.com/discuss@openvswitch.org/msg15373.html
>> ,
>>
>> that trace-route is not implemented yet in OVS.
>
> Well, that discussion is not really related to this since its about traceroute where OVS is a transit switch.
>
>> I need to implement a more enhanced trace-route for vxlan overlay.
>>
>> As we use the OVS as a vTEP device I need to trace-route the actual
>> data-path for a given vxlan-segment (since there are multi ecmp paths
>> – this should traverse a specific path based on the source UDP port)
>>
>> This is  done by transmitting a series an vxlan encapsulated packets with an
>> incremental TTL , IP-destined to the remote vTEP.   an intermediate device
>> (which are generally traditional routers in the underlay)  replies
>> with ICMP ttl expired.
>>
>> 2 questions:
>>
>> -          How to initiate  these packets transmission in the originating
>> vTEP ? can I do it from the vTEP/ a local application ?
>
> Packets can be injected from OVS userspace, similar to STP/BFD. When setting up the encapsulation parameters, you can set the TTL.
>
>> -          How the ICMP  replies  can be delivered/ if any  to a local
>> application that is connected to the vTEP via a TAP device ?
>
> I think you could probably capture ICMP errors using a raw socket.



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