Dear OVS devs, For some experiments I did around April/May for a paper I wrote I changed some sourcecode to ofproto-dpif-xlate.c to have the FastFailover Group Table look at the BFD status directly. We did this because we found that although the BFD status flags changed in time, interface status remained up (which might or might not already have been solved by now) and hence the FastFailover rule would not select the backup forwarding rule. Furthermore, our experiments showed that bringing the interface status down manually could take slightly over 50 ms before the FastFailover would kick in [1]. As we wanted "even faster" recovery, we decided to have the function odp_port_is_alive() also look at the BFD status itself [2]. Doing this also decreased the number of packets when an interface became live again, as the Fast Failover rule would not revert sending to the primary rule before BFD confirmed a live link.
If you are interested I can rewrite the patch to confirm to the appropriate coding lay-out and make sure it applies to the current state of the file. Perhaps instead of checking the BFD status, I could include a *synchronized* per-interface flag that f.e. equals 0x00 when all configured link state detection mechanisms detect live links, 0x01 when BFD detects an error, 0x02 when Ethernet OAM detects an error, 0x03 when both do, etc. In that case you can check status from multiple detection mechanisms without the need to iterate through all of them, hence improving the throughput of OVS. How do you think about that? Best regards, Niels van Adrichem [1] http://www.nas.ewi.tudelft.nl/people/Fernando/papers/EWSDN2014.pdf [2] https://github.com/TUDelftNAS/SDN-OpenFlowRecovery _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
