From 5aa93bcf66f4af094d6f11096e81d5501a0b4ba5 Mon Sep 17 00:00:00 2001 From: Neil Horman Date: Sat, 21 Jul 2012 07:56:07 +0000 Subject: 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 CC: Vlad Yasevich CC: Sridhar Samudrala CC: "David S. Miller" CC: linux-sctp@vger.kernel.org CC: joe@perches.com Acked-by: Vlad Yasevich Signed-off-by: David S. Miller --- Documentation/networking/ip-sysctl.txt | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'Documentation/networking/ip-sysctl.txt') diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index 5f3ef7f7fcec..406a5226220d 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 -- cgit v1.2.3