what "Retr" field mean .

[big-loser]

Does the "Retr" field mean？

Is re-transmitted by TCP ?

Under what circumstances will appear this kind of state?

tks

[bmah888]

It's the number of TCP segments retransmitted. This can happen if TCP segments are lost in the network due to congestion or corruption.

[penglei0]

It's the number of TCP segments retransmitted. This can happen if TCP segments are lost in the network due to congestion or corruption.

@bmah888 It's not the number of retransmitted segments. Actually, it's the number of attempting to retransmit segments; the retransmission attempting may fail and the segment will not be occurs on the outgoing link.

    tcp_enter_loss(sk);

    icsk->icsk_retransmits++;
    if (tcp_retransmit_skb(sk, tcp_rtx_queue_head(sk), 1) > 0) {
        /* Retransmission failed because of local congestion,
         * Let senders fight for local resources conservatively.
         */
        inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
                      TCP_RESOURCE_PROBE_INTERVAL,
                      TCP_RTO_MAX);
        goto out;
    }

[bmah888]

It's the number of TCP segments retransmitted. This can happen if TCP segments are lost in the network due to congestion or corruption.

@bmah888 It's not the number of retransmitted segments. Actually, it's the number of attempting to retransmit segments; the retransmission attempting may fail and the segment will not be occurs on the outgoing link.

Good point, that's a subtle but very important difference.