is inherited.
[see setsockopt(listenfd, SOL_TCP, TCP_CONGESTION, "name" ...) ]
-tcp_cookie_size - INTEGER
- Default size of TCP Cookie Transactions (TCPCT) option, that may be
- overridden on a per socket basis by the TCPCT socket option.
- Values greater than the maximum (16) are interpreted as the maximum.
- Values greater than zero and less than the minimum (8) are interpreted
- as the minimum. Odd values are interpreted as the next even value.
- Default: 0 (off).
-
tcp_dsack - BOOLEAN
Allows TCP to send "duplicate" SACKs.
Default: 60 seconds
tcp_frto - INTEGER
- Enables Forward RTO-Recovery (F-RTO) defined in RFC4138.
+ Enables Forward RTO-Recovery (F-RTO) defined in RFC5682.
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. F-RTO is sender-side
- only modification. Therefore it does not require any support from
- the peer.
-
- 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)
+ timeouts. It is particularly beneficial in networks where the
+ RTT fluctuates (e.g., wireless). F-RTO is sender-side only
+ modification. It does not require any support from the peer.
+
+ By default it's enabled with a non-zero value. 0 disables F-RTO.
tcp_keepalive_time - INTEGER
How often TCP sends out keepalive messages when keepalive is enabled.