// // A simple test to validate RFC6582 // (minimum cwnd after loss recovery >= 2 mss) // // First, cwnd is built up by acking every data segment // // Then we "drop" one packet, and sent // 4 dup ACKs with the appropriate SACK blocks. // // When the retransmission arrives, we do // a cumulative ACK. Depending on how many // Segements are received after that, we // can infer the cwnd size and the behavior // of SACK loss recovery. // Create a listening TCP socket. 0.000 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. +0.035 < S 0:0(0) win 65535 +0.000 > S. 0:0(0) ack 1 win 65535 <...> +0.000 < . 1:1(0) ack 1 win 65535 +0.000 accept(3, ..., ...) = 4 // Write some data to be sent to the simulated // packetdrill receiver. // Note: More than 33kB appears to get stuck on BSD 0.200 write(4, ..., 33000) = 33000 0.2~1 > . 1:1001(1000) ack 1 +0 < . 1:1(0) ack 1001 win 65535 // ACKing every packet 0.2~1 > . 1001:2001(1000) ack 1 +0 < . 1:1(0) ack 2001 win 65535 // to built up cwnd fast 0.2~1 > . 2001:3001(1000) ack 1 +0 < . 1:1(0) ack 3001 win 65535 0.2~1 > . 3001:4001(1000) ack 1 +0 < . 1:1(0) ack 4001 win 65535 0.2~1 > . 4001:5001(1000) ack 1 +0 < . 1:1(0) ack 5001 win 65535 0.2~1 > . 5001:6001(1000) ack 1 +0 < . 1:1(0) ack 6001 win 65535 0.2~1 > . 6001:7001(1000) ack 1 +0 < . 1:1(0) ack 7001 win 65535 0.2~1 > . 7001:8001(1000) ack 1 +0 < . 1:1(0) ack 8001 win 65535 0.2~1 > . 8001:9001(1000) ack 1 +0 < . 1:1(0) ack 9001 win 65535 0.2~1 > . 9001:10001(1000) ack 1 +0 < . 1:1(0) ack 10001 win 65535 0.2~1 > . 10001:11001(1000) ack 1 +0 < . 1:1(0) ack 11001 win 65535 0.2~1 > . 11001:12001(1000) ack 1 +0 < . 1:1(0) ack 12001 win 65535 0.2~1 > . 12001:13001(1000) ack 1 +0 < . 1:1(0) ack 13001 win 65535 0.2~1 > . 13001:14001(1000) ack 1 +0 < . 1:1(0) ack 14001 win 65535 0.2~1 > . 14001:15001(1000) ack 1 +0 < . 1:1(0) ack 15001 win 65535 0.2~1 > . 15001:16001(1000) ack 1 +0 < . 1:1(0) ack 16001 win 65535 0.2~1 > . 16001:17001(1000) ack 1 +0 < . 1:1(0) ack 17001 win 65535 0.2~1 > . 17001:18001(1000) ack 1 +0 < . 1:1(0) ack 18001 win 65535 0.2~1 > . 18001:19001(1000) ack 1 +0 < . 1:1(0) ack 19001 win 65535 0.2~1 > . 19001:20001(1000) ack 1 +0 < . 1:1(0) ack 20001 win 65535 0.2~1 > . 20001:21001(1000) ack 1 +0 write(4, ..., 33000) = 33000 // Inject some additional data +0 < . 1:1(0) ack 21001 win 65535 0.2~1 > . 21001:22001(1000) ack 1 +0 < . 1:1(0) ack 22001 win 65535 0.2~1 > . 22001:23001(1000) ack 1 +0 < . 1:1(0) ack 23001 win 65535 0.2~1 > . 23001:24001(1000) ack 1 +0 < . 1:1(0) ack 24001 win 65535 0.2~1 > . 24001:25001(1000) ack 1 +0 < . 1:1(0) ack 25001 win 65535 0.2~1 > . 25001:26001(1000) ack 1 +0 < . 1:1(0) ack 26001 win 65535 0.2~1 > . 26001:27001(1000) ack 1 +0 < . 1:1(0) ack 27001 win 65535 0.2~1 > . 27001:28001(1000) ack 1 +0 < . 1:1(0) ack 28001 win 65535 0.2~1 > . 28001:29001(1000) ack 1 +0 < . 1:1(0) ack 29001 win 65535 0.2~1 > . 29001:30001(1000) ack 1 +0 < . 1:1(0) ack 30001 win 65535 0.2~1 > . 30001:31001(1000) ack 1 // we "drop" this packet 0.2~1 > . 31001:32001(1000) ack 1 +0 < . 1:1(0) ack 30001 win 65535 // dupack #1 0.2~1 > P. 32001:33001(1000) ack 1 +0 < . 1:1(0) ack 30001 win 65535 // dupack #2 0.2~1 > . 33001:34001(1000) ack 1 +0 < . 1:1(0) ack 30001 win 65535 // dupack #3 0.2~1 > . 34001:35001(1000) ack 1 +0 < . 1:1(0) ack 30001 win 65535 // dupack #4 0.2~1 > . 35001:36001(1000) ack 1 0.2~1 > . 36001:37001(1000) ack 1 0.2~1 > . 37001:38001(1000) ack 1 0.2~1 > . 38001:39001(1000) ack 1 0.2~1 > . 39001:40001(1000) ack 1 0.2~1 > . 40001:41001(1000) ack 1 0.2~1 > . 41001:42001(1000) ack 1 0.2~1 > . 42001:43001(1000) ack 1 0.2~1 > . 43001:44001(1000) ack 1 0.2~1 > . 44001:45001(1000) ack 1 0.2~1 > . 45001:46001(1000) ack 1 0.2~1 > . 46001:47001(1000) ack 1 0.2~1 > . 47001:48001(1000) ack 1 0.2~1 > . 48001:49001(1000) ack 1 0.2~1 > . 49001:50001(1000) ack 1 0.2~1 > . 50001:51001(1000) ack 1 0.2~1 > . 51001:52001(1000) ack 1 0.2~1 > . 52001:53001(1000) ack 1 0.2~1 > . 53001:54001(1000) ack 1 0.2~1 > . 54001:55001(1000) ack 1 0.2~1 > . 55001:56001(1000) ack 1 0.2~1 > . 56001:57001(1000) ack 1 0.2~1 > . 57001:58001(1000) ack 1 0.2~1 > . 58001:59001(1000) ack 1 0.2~1 > . 59001:60001(1000) ack 1 0.2~1 > . 60001:61001(1000) ack 1 0.2~1 > . 61001:62001(1000) ack 1 +0 write(4, ..., 10000) = 10000 0.2~1 > . 62001:63001(1000) ack 1 0.2~1 > . 63001:64001(1000) ack 1 0.2~1 > . 64001:65001(1000) ack 1 0.2~1 > P. 65001:66001(1000) ack 1 0.2~1 > . 30001:31001(1000) ack 1 // we expect the retransmission around here +0 < . 1:1(0) ack 66001 win 65535 // cumulative ACK 0.2~1 > . 66001:67001(1000) ack 1 0.4 < . 1:1(0) ack 67001 win 65535 0.4~1 > . 67001:68001(1000) ack 1 // if cwnd is > 1, we should get these 0.4~1 > . 68001:69001(1000) ack 1 // packets //0.4~1 > . 69001:70001(1000) ack 1 // Also look at the timing when //0.4~1 > . 70001:71001(1000) ack 1 // running packetdrill //0.4~1 > . 71001:72001(1000) ack 1 //0.4~1 > . 72001:73001(1000) ack 1 //0.4~1 > . 73001:74001(1000) ack 1 //0.4~1 > . 74001:75001(1000) ack 1 //0.4~1 > . 75001:76001(1000) ack 1 //0.4~1 > . 76001:77001(1000) ack 1 //0.4~1 > . 77001:78001(1000) ack 1 //0.4~1 > . 78001:79001(1000) ack 1 //0.4~1 > . 79001:80001(1000) ack 1 //0.4~1 > . 80001:81001(1000) ack 1 //0.300 < . 1:1(0) ack 14601 win 65535 2.000 close(4) = 0 //+0 > F. 2001:2001(0) ack 1 +0.1 < F. 1:1(0) ack 11002 win 65535 //0.502 > . 2002:2002(0) ack 2