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Diffstat (limited to 'Documentation/networking/ip-sysctl.rst')
| -rw-r--r-- | Documentation/networking/ip-sysctl.rst | 71 |
1 files changed, 49 insertions, 22 deletions
diff --git a/Documentation/networking/ip-sysctl.rst b/Documentation/networking/ip-sysctl.rst index 9756d16e3df1..a06cb99d66dc 100644 --- a/Documentation/networking/ip-sysctl.rst +++ b/Documentation/networking/ip-sysctl.rst @@ -209,7 +209,7 @@ neigh/default/unres_qlen_bytes - INTEGER Setting negative value is meaningless and will return error. - Default: SK_WMEM_MAX, (same as net.core.wmem_default). + Default: SK_WMEM_DEFAULT, (same as net.core.wmem_default). Exact value depends on architecture and kernel options, but should be enough to allow queuing 256 packets @@ -443,23 +443,56 @@ tcp_early_retrans - INTEGER tcp_ecn - INTEGER Control use of Explicit Congestion Notification (ECN) by TCP. - ECN is used only when both ends of the TCP connection indicate - support for it. This feature is useful in avoiding losses due - to congestion by allowing supporting routers to signal - congestion before having to drop packets. + ECN is used only when both ends of the TCP connection indicate support + for it. This feature is useful in avoiding losses due to congestion by + allowing supporting routers to signal congestion before having to drop + packets. A host that supports ECN both sends ECN at the IP layer and + feeds back ECN at the TCP layer. The highest variant of ECN feedback + that both peers support is chosen by the ECN negotiation (Accurate ECN, + ECN, or no ECN). + + The highest negotiated variant for incoming connection requests + and the highest variant requested by outgoing connection + attempts: + + ===== ==================== ==================== + Value Incoming connections Outgoing connections + ===== ==================== ==================== + 0 No ECN No ECN + 1 ECN ECN + 2 ECN No ECN + 3 AccECN AccECN + 4 AccECN ECN + 5 AccECN No ECN + ===== ==================== ==================== + + Default: 2 + +tcp_ecn_option - INTEGER + Control Accurate ECN (AccECN) option sending when AccECN has been + successfully negotiated during handshake. Send logic inhibits + sending AccECN options regarless of this setting when no AccECN + option has been seen for the reverse direction. Possible values are: - = ===================================================== - 0 Disable ECN. Neither initiate nor accept ECN. - 1 Enable ECN when requested by incoming connections and - also request ECN on outgoing connection attempts. - 2 Enable ECN when requested by incoming connections - but do not request ECN on outgoing connections. - = ===================================================== + = ============================================================ + 0 Never send AccECN option. This also disables sending AccECN + option in SYN/ACK during handshake. + 1 Send AccECN option sparingly according to the minimum option + rules outlined in draft-ietf-tcpm-accurate-ecn. + 2 Send AccECN option on every packet whenever it fits into TCP + option space. + = ============================================================ Default: 2 +tcp_ecn_option_beacon - INTEGER + Control Accurate ECN (AccECN) option sending frequency per RTT and it + takes effect only when tcp_ecn_option is set to 2. + + Default: 3 (AccECN will be send at least 3 times per RTT) + tcp_ecn_fallback - BOOLEAN If the kernel detects that ECN connection misbehaves, enable fall back to non-ECN. Currently, this knob implements the fallback @@ -805,8 +838,8 @@ tcp_rmem - vector of 3 INTEGERs: min, default, max This value results in initial window of 65535. max: maximal size of receive buffer allowed for automatically - selected receiver buffers for TCP socket. This value does not override - net.core.rmem_max. Calling setsockopt() with SO_RCVBUF disables + selected receiver buffers for TCP socket. + Calling setsockopt() with SO_RCVBUF disables automatic tuning of that socket's receive buffer size, in which case this value is ignored. Default: between 131072 and 32MB, depending on RAM size. @@ -3508,16 +3541,10 @@ cookie_hmac_alg - STRING a listening sctp socket to a connecting client in the INIT-ACK chunk. Valid values are: - * md5 - * sha1 + * sha256 * none - Ability to assign md5 or sha1 as the selected alg is predicated on the - configuration of those algorithms at build time (CONFIG_CRYPTO_MD5 and - CONFIG_CRYPTO_SHA1). - - Default: Dependent on configuration. MD5 if available, else SHA1 if - available, else none. + Default: sha256 rcvbuf_policy - INTEGER Determines if the receive buffer is attributed to the socket or to |