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@@ -56,6 +56,11 @@ Daniel-Constantin Mierla
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4.23. failures
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4.24. received_ACKs
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+ 5. Event routes
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+
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+ 5.1. sl:filtered-ack
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+ 5.2. sl:local-response
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+
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List of Examples
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1.1. default_code example
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@@ -111,6 +116,11 @@ Chapter 1. Admin Guide
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4.23. failures
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4.24. received_ACKs
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+ 5. Event routes
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+
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+ 5.1. sl:filtered-ack
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+ 5.2. sl:local-response
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+
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1. Overview
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The SL module allows the SIP server to act as a stateless UA server and
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@@ -119,12 +129,12 @@ Chapter 1. Admin Guide
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memory and scale well.
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The SL module needs to filter ACKs sent after a local stateless reply
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- to an INVITE was generated. To recognize such ACKs, ser adds a special
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- "signature" in to-tags. This signature is sought for in incoming ACKs,
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- and if included, the ACKs are absorbed.
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+ to an INVITE was generated. To recognize such ACKs, Kamailio adds a
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+ special "signature" in to-tags. This signature is sought for in
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+ incoming ACKs, and if included, the ACKs are absorbed.
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To speed up the filtering process, the module uses a timeout mechanism.
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- When a reply is sent, a timer us set. As long as the timer is valid,
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+ When a reply is sent, a timer is set. As long as the timer is valid,
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the incoming ACK requests will be checked using TO tag value. Once the
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timer expires, all the ACK messages are let through - a long time
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passed till it sent a reply, so it does not expect any ACK that have to
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@@ -135,8 +145,9 @@ Chapter 1. Admin Guide
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processing. Particularly, the problem happens when a UA sends an INVITE
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which already has a to-tag in it (e.g., a re-INVITE) and the server
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want to reply to it. Then, it will keep the current to-tag, which will
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- be mirrored in ACK. SER will not see its signature and forward the ACK
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- downstream. Caused harm is not bad--just a useless ACK is forwarded.
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+ be mirrored in ACK. Kamailio will not see its signature and forward the
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+ ACK downstream. Caused harm is not bad, just a useless ACK is
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+ forwarded.
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2. Parameters
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@@ -385,3 +396,27 @@ if(status=="408")
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4.24. received_ACKs
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Number of received ACKs filtered by SL module.
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+
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+5. Event routes
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+
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+ 5.1. sl:filtered-ack
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+ 5.2. sl:local-response
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+
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+5.1. sl:filtered-ack
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+
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+ Executed when ACK to locally generated reply is recognized and
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+ absorbed.
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+...
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+event_route[sl:filtered-ack] {
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+ xlog("sl:filtered-ack ACK to local reply absorbed\n");
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+}
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+...
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+
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+5.2. sl:local-response
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+
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+ Executed after sl module reply function has sent local reply.
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+...
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+event_route[sl:local-response] {
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+ xlog("sl:local-response replied locally\n");
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+}
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+...
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