path: root/Documentation/networking
diff options
authorMarcelo Ricardo Leitner <>2015-02-23 15:02:34 -0300
committerSimon Horman <>2015-02-25 13:46:35 +0900
commitd752c364571743d696c2a54a449ce77550c35ac5 (patch)
tree160b607482c080c720f27626fa7a7130307cbbf3 /Documentation/networking
parent7f73b9f1ca7334eec0ff9a40e37ece92dd3e420f (diff)
ipvs: allow rescheduling of new connections when port reuse is detected
Currently, when TCP/SCTP port reusing happens, IPVS will find the old entry and use it for the new one, behaving like a forced persistence. But if you consider a cluster with a heavy load of small connections, such reuse will happen often and may lead to a not optimal load balancing and might prevent a new node from getting a fair load. This patch introduces a new sysctl, conn_reuse_mode, that allows controlling how to proceed when port reuse is detected. The default value will allow rescheduling of new connections only if the old entry was in TIME_WAIT state for TCP or CLOSED for SCTP. Signed-off-by: Marcelo Ricardo Leitner <> Signed-off-by: Julian Anastasov <> Signed-off-by: Simon Horman <>
Diffstat (limited to 'Documentation/networking')
1 files changed, 21 insertions, 0 deletions
diff --git a/Documentation/networking/ipvs-sysctl.txt b/Documentation/networking/ipvs-sysctl.txt
index 7a3c04729591..3ba709531adb 100644
--- a/Documentation/networking/ipvs-sysctl.txt
+++ b/Documentation/networking/ipvs-sysctl.txt
@@ -22,6 +22,27 @@ backup_only - BOOLEAN
If set, disable the director function while the server is
in backup mode to avoid packet loops for DR/TUN methods.
+conn_reuse_mode - INTEGER
+ 1 - default
+ Controls how ipvs will deal with connections that are detected
+ port reuse. It is a bitmap, with the values being:
+ 0: disable any special handling on port reuse. The new
+ connection will be delivered to the same real server that was
+ servicing the previous connection. This will effectively
+ disable expire_nodest_conn.
+ bit 1: enable rescheduling of new connections when it is safe.
+ That is, whenever expire_nodest_conn and for TCP sockets, when
+ the connection is in TIME_WAIT state (which is only possible if
+ you use NAT mode).
+ bit 2: it is bit 1 plus, for TCP connections, when connections
+ are in FIN_WAIT state, as this is the last state seen by load
+ balancer in Direct Routing mode. This bit helps on adding new
+ real servers to a very busy cluster.
conntrack - BOOLEAN
0 - disabled (default)
not 0 - enabled