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authorAlex Bergmann <alex@linlab.net>2012-08-31 02:48:31 +0000
committerDavid S. Miller <davem@davemloft.net>2012-08-31 15:42:10 -0400
commit6c9ff979d1921e9fd05d89e1383121c2503759b9 (patch)
tree410b5538e913215285e83e88c1392f307e9799d6 /Documentation/networking
parentc32f38619af6302da58835fb292b159bdd96d11f (diff)
downloadlinaro-lsk-6c9ff979d1921e9fd05d89e1383121c2503759b9.tar.gz
tcp: Increase timeout for SYN segments
Commit 9ad7c049 ("tcp: RFC2988bis + taking RTT sample from 3WHS for the passive open side") changed the initRTO from 3secs to 1sec in accordance to RFC6298 (former RFC2988bis). This reduced the time till the last SYN retransmission packet gets sent from 93secs to 31secs. RFC1122 is stating that the retransmission should be done for at least 3 minutes, but this seems to be quite high. "However, the values of R1 and R2 may be different for SYN and data segments. In particular, R2 for a SYN segment MUST be set large enough to provide retransmission of the segment for at least 3 minutes. The application can close the connection (i.e., give up on the open attempt) sooner, of course." This patch increases the value of TCP_SYN_RETRIES to the value of 6, providing a retransmission window of 63secs. The comments for SYN and SYNACK retries have also been updated to describe the current settings. The same goes for the documentation file "Documentation/networking/ip-sysctl.txt". Signed-off-by: Alexander Bergmann <alex@linlab.net> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/networking')
-rw-r--r--Documentation/networking/ip-sysctl.txt8
1 files changed, 6 insertions, 2 deletions
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index ca447b35b83..d64e53124b8 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -439,7 +439,9 @@ tcp_stdurg - BOOLEAN
tcp_synack_retries - INTEGER
Number of times SYNACKs for a passive TCP connection attempt will
be retransmitted. Should not be higher than 255. Default value
- is 5, which corresponds to ~180seconds.
+ is 5, which corresponds to 31seconds till the last retransmission
+ with the current initial RTO of 1second. With this the final timeout
+ for a passive TCP connection will happen after 63seconds.
tcp_syncookies - BOOLEAN
Only valid when the kernel was compiled with CONFIG_SYNCOOKIES
@@ -478,7 +480,9 @@ tcp_fastopen - INTEGER
tcp_syn_retries - INTEGER
Number of times initial SYNs for an active TCP connection attempt
will be retransmitted. Should not be higher than 255. Default value
- is 5, which corresponds to ~180seconds.
+ is 6, which corresponds to 63seconds till the last restransmission
+ with the current initial RTO of 1second. With this the final timeout
+ for an active TCP connection attempt will happen after 127seconds.
tcp_timestamps - BOOLEAN
Enable timestamps as defined in RFC1323.