path: root/Documentation/networking
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authorNeil Horman <nhorman@tuxdriver.com>2012-07-21 07:56:07 +0000
committerDavid S. Miller <davem@davemloft.net>2012-07-22 12:13:46 -0700
commit5aa93bcf66f4af094d6f11096e81d5501a0b4ba5 (patch)
tree7bcf045fcae31a7e367e7eb1e0568b3702a25018 /Documentation/networking
parente3906486f616da7cc086a3ba06c0df4e5a48b4ab (diff)
sctp: Implement quick failover draft from tsvwg
I've seen several attempts recently made to do quick failover of sctp transports by reducing various retransmit timers and counters. While its possible to implement a faster failover on multihomed sctp associations, its not particularly robust, in that it can lead to unneeded retransmits, as well as false connection failures due to intermittent latency on a network. Instead, lets implement the new ietf quick failover draft found here: http://tools.ietf.org/html/draft-nishida-tsvwg-sctp-failover-05 This will let the sctp stack identify transports that have had a small number of errors, and avoid using them quickly until their reliability can be re-established. I've tested this out on two virt guests connected via multiple isolated virt networks and believe its in compliance with the above draft and works well. Signed-off-by: Neil Horman <nhorman@tuxdriver.com> CC: Vlad Yasevich <vyasevich@gmail.com> CC: Sridhar Samudrala <sri@us.ibm.com> CC: "David S. Miller" <davem@davemloft.net> CC: linux-sctp@vger.kernel.org CC: joe@perches.com Acked-by: Vlad Yasevich <vyasevich@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'Documentation/networking')
1 files changed, 14 insertions, 0 deletions
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt
index 5f3ef7f7fce..406a5226220 100644
--- a/Documentation/networking/ip-sysctl.txt
+++ b/Documentation/networking/ip-sysctl.txt
@@ -1440,6 +1440,20 @@ path_max_retrans - INTEGER
Default: 5
+pf_retrans - INTEGER
+ The number of retransmissions that will be attempted on a given path
+ before traffic is redirected to an alternate transport (should one
+ exist). Note this is distinct from path_max_retrans, as a path that
+ passes the pf_retrans threshold can still be used. Its only
+ deprioritized when a transmission path is selected by the stack. This
+ setting is primarily used to enable fast failover mechanisms without
+ having to reduce path_max_retrans to a very low value. See:
+ http://www.ietf.org/id/draft-nishida-tsvwg-sctp-failover-05.txt
+ for details. Note also that a value of pf_retrans > path_max_retrans
+ disables this feature
+ Default: 0
rto_initial - INTEGER
The initial round trip timeout value in milliseconds that will be used
in calculating round trip times. This is the initial time interval