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test-cwnd-collapse.pkt
rscheff (Richard Scheffenegger)
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rscheff
Jan 24 2020, 9:15 PM
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test-cwnd-collapse.pkt
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// A simple server-side test that sends exactly an initial window (IW10)
// worth of packets.
--tolerance_usecs=250000
// Flush Hostcache
+0.00 `sysctl net.inet.tcp.ecn.enable=1`
//+0.02 `kldload -n cc_cubic`
+0.02 `sysctl net.inet.tcp.cc.algorithm=cubic`
+0.02 `sysctl net.inet.tcp.hostcache.purgenow=1`
// Create a listening TCP socket.
0.100 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+0.005 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
+0.005 bind(3, ..., ...) = 0
+0.005 listen(3, 1) = 0
// Establish a TCP connection without ECN
+0.035 <[noecn] SEW 0:0(0) win 65535 <mss 1000, sackOK, eol, eol>
+0.000 >[noecn] SE. 0:0(0) ack 1 win 65535 <...>
+0.000 <[noecn] . 1:1(0) ack 1 win 65535
+0.000 accept(3, ..., ...) = 4
+0 %{ print "cwnd\twnd \tssthresh\tNXT" }%
+0 %{ print "{}\t{}\t{}\t{}".format(tcpi_snd_cwnd, tcpi_snd_wnd, tcpi_snd_ssthresh, tcpi_snd_nxt) }%
// simulate NFS request/response w/ ECN mark
+0.1 <[ce] P. 1:101(100) ack 1 win 65535
+0 read(4, ..., 100) = 100
+0 write (4, ..., 100) = 100
+0 >[ect0] PE. 1:101(100) ack 101
+0 <[noecn] E. 101:101(0) ack 101 win 65535
+0 %{ print "{}\t{}\t{}\t{}".format(tcpi_snd_cwnd, tcpi_snd_wnd, tcpi_snd_ssthresh, tcpi_snd_nxt) }%
+0.001 <[ce] PEW. 101:201(100) ack 101 win 65535
+0 read(4, ..., 100) = 100
+0 write (4, ..., 100) = 100
+0 >[ect0] PEW. 101:201(100) ack 201
+0 <[noecn] E. 201:201(0) ack 201 win 65535
+0 %{ print "{}\t{}\t{}\t{}".format(tcpi_snd_cwnd, tcpi_snd_wnd, tcpi_snd_ssthresh, tcpi_snd_nxt) }%
+0.001 <[ce] PEW. 201:301(100) ack 201 win 65535
+0 read(4, ..., 100) = 100
+0 write (4, ..., 100) = 100
+0 >[ect0] PEW. 201:301(100) ack 301
+0 <[noecn] E. 301:301(0) ack 301 win 65535
+0 %{ print "{}\t{}\t{}\t{}".format(tcpi_snd_cwnd, tcpi_snd_wnd, tcpi_snd_ssthresh, tcpi_snd_nxt) }%
+0.001 <[ce] PEW. 301:401(100) ack 301 win 65535
+0 read(4, ..., 100) = 100
+0 write (4, ..., 100) = 100
+0 >[ect0] PEW. 301:401(100) ack 401
+0 <[noecn] E. 401:401(0) ack 401 win 65535
+0 %{ print "{}\t{}\t{}\t{}".format(tcpi_snd_cwnd, tcpi_snd_wnd, tcpi_snd_ssthresh, tcpi_snd_nxt) }%
+0.001 <[ce] PEW. 401:501(100) ack 401 win 65535
+0 read(4, ..., 100) = 100
+0 write (4, ..., 100) = 100
+0 >[ect0] PEW. 401:501(100) ack 501
+0 <[noecn] E. 501:501(0) ack 501 win 65535
+0 %{ print "{}\t{}\t{}\t{}".format(tcpi_snd_cwnd, tcpi_snd_wnd, tcpi_snd_ssthresh, tcpi_snd_nxt) }%
+0.001 <[ce] PEW. 501:601(100) ack 501 win 65535
+0 read(4, ..., 100) = 100
+0 write (4, ..., 100) = 100
+0 >[ect0] PEW. 501:601(100) ack 601
+0 <[noecn] E. 601:601(0) ack 601 win 65535
+0 %{ print "{}\t{}\t{}\t{}".format(tcpi_snd_cwnd, tcpi_snd_wnd, tcpi_snd_ssthresh, tcpi_snd_nxt) }%
+0.001 <[ce] PEW. 601:701(100) ack 601 win 65535
+0 read(4, ..., 100) = 100
+0 write (4, ..., 100) = 100
+0 >[ect0] PEW. 601:701(100) ack 701
+0 <[noecn] E. 701:701(0) ack 701 win 65535
+0 %{ print "{}\t{}\t{}\t{}".format(tcpi_snd_cwnd, tcpi_snd_wnd, tcpi_snd_ssthresh, tcpi_snd_nxt) }%
+0.001 <[ce] PEW. 701:801(100) ack 701 win 65535
+0 read(4, ..., 100) = 100
+0 write (4, ..., 100) = 100
+0 >[ect0] PEW. 701:801(100) ack 801
+0 <[noecn] E. 801:801(0) ack 801 win 65535
+0 %{ print "{}\t{}\t{}\t{}".format(tcpi_snd_cwnd, tcpi_snd_wnd, tcpi_snd_ssthresh, tcpi_snd_nxt) }%
+0.001 <[ce] PEW. 801:901(100) ack 801 win 65535
+0 read(4, ..., 100) = 100
+0 write (4, ..., 100) = 100
+0 >[ect0] PEW. 801:901(100) ack 901
+0 <[noecn] E. 901:901(0) ack 901 win 65535
+0 %{ print "{}\t{}\t{}\t{}".format(tcpi_snd_cwnd, tcpi_snd_wnd, tcpi_snd_ssthresh, tcpi_snd_nxt) }%
+0.001 <[ce] PEW. 901:1001(100) ack 901 win 65535
+0 read(4, ..., 100) = 100
+0 write (4, ..., 100) = 100
+0 >[ect0] PEW. 901:1001(100) ack 1001
+0 <[noecn] E. 1001:1001(0) ack 1001 win 65535
+0 %{ print "{}\t{}\t{}\t{}".format(tcpi_snd_cwnd, tcpi_snd_wnd, tcpi_snd_ssthresh, tcpi_snd_nxt) }%
+0.001 <[ce] PEW. 1001:1101(100) ack 1001 win 65535
+0 read(4, ..., 100) = 100
+0 write (4, ..., 100) = 100
+0 >[ect0] PEW. 1001:1101(100) ack 1101
+0 <[noecn] E. 1101:1101(0) ack 1101 win 65535
+0 %{ print "{}\t{}\t{}\t{}".format(tcpi_snd_cwnd, tcpi_snd_wnd, tcpi_snd_ssthresh, tcpi_snd_nxt) }%
+0.001 <[ce] PEW. 1101:1201(100) ack 1101 win 65535
+0 read(4, ..., 100) = 100
+0 write (4, ..., 100) = 100
// Problematic behavior. MSS should always be at least 1000 bytes, a small RPC should never be
// sent in more than a single packet.
+0 >[ect0] EW. 1101:1197(96) ack 1201
+0 <[noecn] E. 1201:1201(0) ack 1197 win 65535
+0 >[ect0] PE. 1197:1201(4) ack 1201
+0 %{ print "{}\t{}\t{}\t{}".format(tcpi_snd_cwnd, tcpi_snd_wnd, tcpi_snd_ssthresh, tcpi_snd_nxt) }%
+0.001 <[ce] PEW. 1201:1301(100) ack 1201 win 65535
+0 read(4, ..., 100) = 100
+0 write (4, ..., 100) = 100
+0 >[ect0] EW. 1201:1268(67) ack 1301
+0 <[noecn] E. 1301:1301(0) ack 1268 win 65535
+0 >[ect0] PEW. 1268:1301(33) ack 1301
+0 %{ print "{}\t{}\t{}\t{}".format(tcpi_snd_cwnd, tcpi_snd_wnd, tcpi_snd_ssthresh, tcpi_snd_nxt) }%
+0.001 <[ce] PEW. 1301:1401(100) ack 1301 win 65535
+0 read(4, ..., 100) = 100
+0 write (4, ..., 100) = 100
// Checking if Cubic+ECN really collapses down to 1 byte
+0 >[ect0] EW. 1301:1333(32) ack 1401
+0 <[noecn] E. 1401:1401(0) ack 1333 win 65535
+0~+5 >[ect0] EW. 1333:1355(22) ack 1401
+0 <[noecn] E. 1401:1401(0) ack 1355 win 65535
+0~+5 >[ect0] EW. 1355:1370(15) ack 1401
+0 <[noecn] E. 1401:1401(0) ack 1370 win 65535
+0~+5 >[ect0] EW. 1370:1380(10) ack 1401
+0 <[noecn] E. 1401:1401(0) ack 1380 win 65535
+0~+5 >[ect0] EW. 1380:1386(6) ack 1401
+0 <[noecn] E. 1401:1401(0) ack 1386 win 65535
+0~+5 >[ect0] EW. 1386:1390(4) ack 1401
+0 <[noecn] E. 1401:1401(0) ack 1390 win 65535
+0~+5 >[ect0] EW. 1390:1392(2) ack 1401
+0 <[noecn] E. 1401:1401(0) ack 1392 win 65535
+0~+5 >[ect0] EW. 1392:1393(1) ack 1401
+0 <[noecn] E. 1401:1401(0) ack 1393 win 65535
+0~+5 >[ect0] EW. 1393:1394(1) ack 1401
+0 <[noecn] E. 1401:1401(0) ack 1394 win 65535
+0~+5 >[ect0] EW. 1394:1395(1) ack 1401
+0 <[noecn] E. 1401:1401(0) ack 1395 win 65535
+0 %{ print "{}\t{}\t{}\t{}".format(tcpi_snd_cwnd, tcpi_snd_wnd, tcpi_snd_ssthresh, tcpi_snd_nxt) }%
+0.100 close(4) = 0
//+0 <[noecn] F. 5001:5001(0) ack 5001 win 65535
//+0 >[noecn] F. 5001:5001(0) ack 5001
//+0 <[noecn] . 5002:5002(0) ack 5002 win 65535
//+0 >[noecn] F. 5001:5001(0) ack 5002
// Restore default sysctls
`sysctl net.inet.tcp.ecn.enable=2; sysctl net.inet.tcp.cc.algorithm=newreno`

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