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Re: [ovs-discuss] bfd implementation in OVS

Alex Wang <alexw@...>
 



On Tue, Aug 25, 2015 at 4:57 AM, daya kamath <daya_k@...> wrote:
hi ,
i would like some clarification on the BFD implementation in OVS.

http://openvswitch.org/pipermail/discuss/2015-February/016515.html indicates the BFD is not multi-hop but sent through the tunnel.

can someone please clarify, if i create a VXLAN tunnel between 2 OVS switches over a WAN,
1. will the BFD work, i.e will BFD packets be VXLAN encapsulated, and delivered as if it were a single hop? 


You need to create a vlxan tunnel between the two host first,

and then enable bfd on the tunnel ports on both end,

yes, bfd pkt will be delivered as single hop,

 
2. if yes, how does the OVS detect BFD payload after stripping off the VXLAN header on an incoming packet?


UDP port,

please check the function bfd_should_process_flow() in bfd.c module for details,

 
3. what does the VTEP put in the inner source and dest IP fields for BFD pkts? does it put the same values as the outer header?



Some hardware switch also requires specific inner bfd header fields, so these fields are for
compatibility

Since ovs only checks the udp port, you do not need to care about it, please refer to
function bfd_put_packet() in bfd.c module for how bfd packet is composed,

Thanks,
Alex Wang,

 
thanks!



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