Dear Ben, thank you for your response. I am currently continue to test OVS and investigated another following problem:
I increase number the load - 500 UDP flows with 10 consequent packets in each of them sent in 0.2 sec interval. miss_send_len is set to 65535, no rules are installed to OVS, so it should generate 5000 Packet_In messages to controller re-sending full packet (180 bytes size in tests). 1. ovs-dpctl -s show br0 - shows 5000 packets on ingress interface and all of them marked as missed (or part f then as hit because of being in the same flow) and passed to user-space (no drops or lost packets) 2. ovs-ofctl dump-ports, dump-tables - shows the same: 5000 packet processed 3. ovs-appctl bridge/dump-flows br0 - shows that 5000 packets sent to controller: table_id=254, duration=11s, priority=0, n_packets=5000, n_bytes=810000, priority=0, reg0=0x1, actions=controller(reason=no_match) 4. ovs-vswitchd.log shows only shrinking of hash table and no other warnings or infos However when I run tcpdump on loopback beetween OVS and controller I see that only part of Packet_In appears there (around 3800 out of 5000). I calculate it according to number of bytes transferred to controller, because part of packet_In are joined into tcp segments (with up to MTU = 16384), no drops in kernel is shown. The same number of Packet_In messages (~3800) are parsed and received by controller. The same shows statistics of Lo interface - the same number of packets and bytes appeared and no drops (no more other traffic on this loopback except hello's) If I decrease number of flows (or packets per flow) such that total number of packets < 3500 then all of them arrive to controller. Is it possible that OVS becomes overloaded with high number of incoming packets and generate Packet_In messages not to all of them without logging it? On 25 November 2013 19:08, Ben Pfaff <b...@nicira.com> wrote: > On Mon, Nov 25, 2013 at 03:15:07PM +0100, Anton Matsiuk wrote: > > as Open vSwitch stores only 256 Packet_Ins in buffer > (OFPT_FEATURES_REPLY: > > n_buffers = 256) after 256 packets it sets Buffer_ID to 0xffffffff. > > Controller didn't check this value as incorrect and placed it into > > responses in flow_mods and packet_outs, that caused packet drops after > > approximately 300 packet_in in a burst. > > > > BTW, setting miss_send_len = 65535 forces switch to send complete > Packet_In > > to Controller but switch still stores packets in buffer and adds valid > > buffer_id for first 255 of them. Is it possible to turn off buffering in > > switch (and to set buffer_id = -1 for all packets) using OpenFlow 1.0? > (In > > OpenFlow 1.2+ it should be possible by setting OFPCML_NO_BUFFER as I > > understood). > > I think that we recently changed OVS to not buffer any packets sent > with a miss_send_len of 65535. Have you tried with OVS 2.0 or later? > > > Is it possible to vary the size of buffer for Packet_In in Open vSwitch? > > No, this is the first request I've heard for that feature. (I've > often thought about just removing packet buffering entirely, it's > always been optional in OpenFlow and I'm not convinced it is useful.) >
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