Hi all, Looking on TCP implementation in Linux I see that there are some things that I don't understand in tcp_mtu_probe() implementation. Could someone clear them for me or share the link to Linux PMTUD documentation, please? The first thing I don't understand is tp->snd_cwnd < 11 in if (!icsk->icsk_mtup.enabled || icsk->icsk_mtup.probe_size || inet_csk(sk)->icsk_ca_state != TCP_CA_Open || tp->snd_cwnd < 11 || tp->rx_opt.num_sacks || tp->rx_opt.dsack) return -1; What is magic number "11" here? The other question is about size_needed variable. It is assigned to value probe_size + (tp->reordering + 1) * tp->mss_cache And that is not clear for me. What is this "(tp->reordering + 1) * tp->mss_cache" addition? Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-newbie" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.linux-learn.org/faqs