More congestion control algorithms may be available as modules,
but not loaded.
+tcp_base_mss - INTEGER
+ The initial value of search_low to be used by Packetization Layer
+ Path MTU Discovery (MTU probing). If MTU probing is enabled,
+ this is the inital MSS used by the connection.
+
tcp_congestion_control - STRING
Set the congestion control algorithm to be used for new
connections. The algorithm "reno" is always available, but
because they eat maximum 1.5K of memory, but they tend
to live longer. Cf. tcp_max_orphans.
-tcp_frto - BOOLEAN
- Enables F-RTO, an enhanced recovery algorithm for TCP retransmission
+tcp_frto - INTEGER
+ Enables Forward RTO-Recovery (F-RTO) defined in RFC4138.
+ F-RTO is an enhanced recovery algorithm for TCP retransmission
timeouts. It is particularly beneficial in wireless environments
where packet loss is typically due to random radio interference
- rather than intermediate router congestion.
+ rather than intermediate router congestion. F-RTO is sender-side
+ only modification. Therefore it does not require any support from
+ the peer, but in a typical case, however, where wireless link is
+ the local access link and most of the data flows downlink, the
+ faraway servers should have F-RTO enabled to take advantage of it.
+ If set to 1, basic version is enabled. 2 enables SACK enhanced
+ F-RTO if flow uses SACK. The basic version can be used also when
+ SACK is in use though scenario(s) with it exists where F-RTO
+ interacts badly with the packet counting of the SACK enabled TCP
+ flow.
+
+tcp_frto_response - INTEGER
+ When F-RTO has detected that a TCP retransmission timeout was
+ spurious (i.e, the timeout would have been avoided had TCP set a
+ longer retransmission timeout), TCP has several options what to do
+ next. Possible values are:
+ 0 Rate halving based; a smooth and conservative response,
+ results in halved cwnd and ssthresh after one RTT
+ 1 Very conservative response; not recommended because even
+ though being valid, it interacts poorly with the rest of
+ Linux TCP, halves cwnd and ssthresh immediately
+ 2 Aggressive response; undoes congestion control measures
+ that are now known to be unnecessary (ignoring the
+ possibility of a lost retransmission that would require
+ TCP to be more cautious), cwnd and ssthresh are restored
+ to the values prior timeout
+ Default: 0 (rate halving based)
tcp_keepalive_time - INTEGER
How often TCP sends out keepalive messages when keepalive is enabled.
Defaults are calculated at boot time from amount of available
memory.
+tcp_moderate_rcvbuf - BOOLEAN
+ If set, TCP performs receive buffer autotuning, attempting to
+ automatically size the buffer (no greater than tcp_rmem[2]) to
+ match the size required by the path for full throughput. Enabled by
+ default.
+
+tcp_mtu_probing - INTEGER
+ Controls TCP Packetization-Layer Path MTU Discovery. Takes three
+ values:
+ 0 - Disabled
+ 1 - Disabled by default, enabled when an ICMP black hole detected
+ 2 - Always enabled, use initial MSS of tcp_base_mss.
+
+tcp_no_metrics_save - BOOLEAN
+ By default, TCP saves various connection metrics in the route cache
+ when the connection closes, so that connections established in the
+ near future can use these to set initial conditions. Usually, this
+ increases overall performance, but may sometimes cause performance
+ degradation. If set, TCP will not cache metrics on closing
+ connections.
+
tcp_orphan_retries - INTEGER
How may times to retry before killing TCP connection, closed
by our side. Default value 7 corresponds to ~50sec-16min
not receive a window scaling option from them.
Default: 0
+tcp_dma_copybreak - INTEGER
+ Lower limit, in bytes, of the size of socket reads that will be
+ offloaded to a DMA copy engine, if one is present in the system
+ and CONFIG_NET_DMA is enabled.
+ Default: 4096
+
+UDP variables:
+
+udp_mem - vector of 3 INTEGERs: min, pressure, max
+ Number of pages allowed for queueing by all UDP sockets.
+
+ min: Below this number of pages UDP is not bothered about its
+ memory appetite. When amount of memory allocated by UDP exceeds
+ this number, UDP starts to moderate memory usage.
+
+ pressure: This value was introduced to follow format of tcp_mem.
+
+ max: Number of pages allowed for queueing by all UDP sockets.
+
+ Default is calculated at boot time from amount of available memory.
+
+udp_rmem_min - INTEGER
+ Minimal size of receive buffer used by UDP sockets in moderation.
+ Each UDP socket is able to use the size for receiving data, even if
+ total pages of UDP sockets exceed udp_mem pressure. The unit is byte.
+ Default: 4096
+
+udp_wmem_min - INTEGER
+ Minimal size of send buffer used by UDP sockets in moderation.
+ Each UDP socket is able to use the size for sending data, even if
+ total pages of UDP sockets exceed udp_mem pressure. The unit is byte.
+ Default: 4096
+
CIPSOv4 Variables:
cipso_cache_enable - BOOLEAN
Functional default: enabled if local forwarding is disabled.
disabled if local forwarding is enabled.
+accept_source_route - INTEGER
+ Accept source routing (routing extension header).
+
+ >= 0: Accept only routing header type 2.
+ < 0: Do not accept routing header.
+
+ Default: 0
+
autoconf - BOOLEAN
Autoconfigure addresses using Prefix Information in Router
Advertisements.
Default: 1
bridge-nf-filter-vlan-tagged - BOOLEAN
- 1 : pass bridged vlan-tagged ARP/IP traffic to arptables/iptables.
+ 1 : pass bridged vlan-tagged ARP/IP/IPv6 traffic to {arp,ip,ip6}tables.
+ 0 : disable this.
+ Default: 1
+
+bridge-nf-filter-pppoe-tagged - BOOLEAN
+ 1 : pass bridged pppoe-tagged IP/IPv6 traffic to {ip,ip6}tables.
0 : disable this.
Default: 1