Hi all, NICETIES tcpreplay version: 4.1.0; CentOS 6.7; x86_64 Multiple Solarflare SFC9120
BACKGROUND: Our application can be built to use one of: * kernel sockets * OpenOnload (bespoke network stack, kernel bypass) * ef_vi (direct to/from VNICs, no stack) PROBLEM: * We test using tcpreplay of captured live multicast packets. * Replayed packets go out eth1 to the switch and back to eth2. * When application is built to use onload or ef_vi, it works as expected. * However when built for kernel stack, replayed packets arrive at eth2 as expected, but are subsequently dropped by kernel. DETAIL: * Multicast drops appear to originate from 2 spots in the linux stack: most from ip_rcv(), and some in tpacket_rcv() (the AF_PACKET stuff) * Captured live data is massaged for playback thusly, addresses redacted: tcprewrite -C --srcipmap=nnn.nnn.nnn.nnn/26:nnn.nnn.nnn.nnn --dstipmap=nnn.nnn.nnn.nnn/24:nnn.nnn.nnn.nnn/24 --enet-smac=00:0F:53:xx:yy:zz --enet-vlan=del -i in.pcap -o out.pcap * All mods and IP checksums look good in Wireshark, and again, the application receives expected flow if the kernel stack is not involved. QUESTION: * Of course I noted the caveat about replay on the same box; however I was not certain that the caveat applied to our use case, tcpreplay -> eth1 -> switch -> eth2 ->kernel; however drops from kernel's tpacket_rcv() would seem to suggest yes? * So is tcpreplay running concurrently with our application likely to be the cause of the kernel dropping multicast packets in this situation? Thanks very much for any assistance you can provide. james ------------------------------------------------------------------------------ Attend Shape: An AT&T Tech Expo July 15-16. Meet us at AT&T Park in San Francisco, CA to explore cutting-edge tech and listen to tech luminaries present their vision of the future. This family event has something for everyone, including kids. Get more information and register today. http://sdm.link/attshape _______________________________________________ Tcpreplay-users mailing list Tcpreplay-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/tcpreplay-users Support Information: http://tcpreplay.synfin.net/trac/wiki/Support
