SIP User's Manual 382 Document #: LTRT-65415
MediaPack Series
Parameter Description
[UsePingPongKeepAlive]
Determines whether the carriage-return and line-feed
sequences (CRLF) Keep-Alive mechanism, according to RFC
5626 “Managing Client-Initiated Connections in the Session
Initiation Protocol (SIP)” is used for reliable, connection-
orientated transport types such as TCP.
[0] Disable (default)
[1] Enable
The SIP user agent/client (i.e., device) uses a simple periodic
message as a keep-alive mechanism to keep their flow to the
proxy or registrar alive (used for example, to keep NAT
bindings open). For connection-oriented transports such as
TCP/TLS this is based on CRLF. This mechanism uses a
client-to-server "ping" keep-alive and a corresponding server-
to-client "pong" message. This ping-pong sequence allows the
client, and optionally the server, to tell if its flow is still active
and useful for SIP traffic. If the client does not receive a pong
in response to its ping, it declares the flow “dead” and opens a
new flow in its place. In the CRLF Keep-Alive mechanism the
client periodically (defined by the PingPongKeepAliveTime
parameter) sends a double-CRLF (the "ping") then waits to
receive a single CRLF (the "pong"). If the client does not
receive a "pong" within an appropriate amount of time, it
considers the flow failed.
Note: The device sends a CRLF message to the Proxy Set
only if the Proxy Keep-Alive feature (EnableProxyKeepAlive
parameter) is enabled and its transport type is set to TCP or
TLS. The device first sends a SIP OPTION message to
establish the TCP/TLS connection and if it receives any SIP
response, it continues sending the CRLF keep-alive
sequences.
[PingPongKeepAliveTime]
Defines the periodic interval (in seconds) after which a “ping”
(double-CRLF) keep-alive is sent to a proxy/registrar, using the
CRLF Keep-Alive mechanism.
The default range is 5 to 2,000,000. The default is 120.
The device uses the range of 80-100% of this user-defined
value as the actual interval. For example, if the parameter
value is set to 200 sec, the interval used is any random time
between 160 to 200 seconds. This prevents an “avalanche” of
keep-alive by multiple SIP UAs to a specific server.
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