36.2. 准备 RHEL 启用 MPTCP 支持

流程

1. 在内核中启用 MPTCP 套接字：

   # echo "net.mptcp.enabled=1" > /etc/sysctl.d/90-enable-MPTCP.conf
   # sysctl -p /etc/sysctl.d/90-enable-MPTCP.conf

2. 启动 iperf3 服务器，并强制它创建 MPTCP 套接字而不是 TCP 套接字：

   # mptcpize run iperf3 -s
   
   Server listening on 5201

3. 将客户端连接到服务器，并强制它创建 MPTCP 套接字而不是 TCP 套接字：

   # mptcpize iperf3 -c 127.0.0.1 -t 3

4. 建立连接后，验证 ss 输出以查看特定于子流的状态：

   # ss -nti '( dport :5201 )'
   
   State Recv-Q Send-Q Local Address:Port Peer Address:Port Process
   ESTAB 0      0      127.0.0.1:41842    127.0.0.1:5201
   cubic wscale:7,7 rto:205 rtt:4.455/8.878 ato:40 mss:21888 pmtu:65535 rcvmss:536 advmss:65483 cwnd:10 bytes_sent:141 bytes_acked:142 bytes_received:4 segs_out:8 segs_in:7 data_segs_out:3 data_segs_in:3 send 393050505bps lastsnd:2813 lastrcv:2772 lastack:2772 pacing_rate 785946640bps delivery_rate 10944000000bps delivered:4 busy:41ms rcv_space:43690 rcv_ssthresh:43690 minrtt:0.008 tcp-ulp-mptcp flags:Mmec token:0000(id:0)/2ff053ec(id:0) seq:3e2cbea12d7673d4 sfseq:3 ssnoff:ad3d00f4 maplen:2

5. 验证 MPTCP 计数器：

   # nstat MPTcp*
   
   #kernel
   MPTcpExtMPCapableSYNRX          2                  0.0
   MPTcpExtMPCapableSYNTX          2                  0.0
   MPTcpExtMPCapableSYNACKRX       2                  0.0
   MPTcpExtMPCapableACKRX          2                  0.0