diff options
| -rw-r--r-- | Documentation/networking/ip-sysctl.txt | 11 | ||||
| -rw-r--r-- | net/ipv4/tcp_input.c | 2 | ||||
| -rw-r--r-- | net/ipv4/tcp_output.c | 2 |
3 files changed, 12 insertions, 3 deletions
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index ec5de02f543f..7f98aa3962c6 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -168,7 +168,16 @@ tcp_dsack - BOOLEAN Allows TCP to send "duplicate" SACKs. tcp_ecn - BOOLEAN - Enable Explicit Congestion Notification in TCP. + Enable Explicit Congestion Notification (ECN) in TCP. ECN is only + used when both ends of the TCP flow support it. It is useful to + avoid losses due to congestion (when the bottleneck router supports + ECN). + Possible values are: + 0 disable ECN + 1 ECN enabled + 2 Only server-side ECN enabled. If the other end does + not support ECN, behavior is like with ECN disabled. + Default: 2 tcp_fack - BOOLEAN Enable FACK congestion avoidance and fast retransmission. diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index c96a6bb25430..56dcf97a97fb 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -77,7 +77,7 @@ int sysctl_tcp_window_scaling __read_mostly = 1; int sysctl_tcp_sack __read_mostly = 1; int sysctl_tcp_fack __read_mostly = 1; int sysctl_tcp_reordering __read_mostly = TCP_FASTRETRANS_THRESH; -int sysctl_tcp_ecn __read_mostly; +int sysctl_tcp_ecn __read_mostly = 2; int sysctl_tcp_dsack __read_mostly = 1; int sysctl_tcp_app_win __read_mostly = 31; int sysctl_tcp_adv_win_scale __read_mostly = 2; diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index 59aec609cec6..79c39dc9b01c 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -288,7 +288,7 @@ static inline void TCP_ECN_send_syn(struct sock *sk, struct sk_buff *skb) struct tcp_sock *tp = tcp_sk(sk); tp->ecn_flags = 0; - if (sysctl_tcp_ecn) { + if (sysctl_tcp_ecn == 1) { TCP_SKB_CB(skb)->flags |= TCPCB_FLAG_ECE | TCPCB_FLAG_CWR; tp->ecn_flags = TCP_ECN_OK; } |
