The Keep Alive is a time interval measured in seconds. Expressed as a 16-bit word, it is the maximum time
interval that is permitted to elapse between the point at which the Client finishes transmitting one Control
Packet and the point it starts sending the next. It is the responsibility of the Client to ensure that the
interval between Control Packets being sent does not exceed the Keep Alive value.
In the absence of sending any other Control Packets, the Client MUST send a PINGREQ Packet.
The Client can send PINGREQ at any time, irrespective of the Keep Alive value, and use the PINGRESP to determine
that the network and the Server are working.
If the Keep Alive value is non-zero and the Server does not receive a Control Packet from the Client within
one and a half times the Keep Alive time period, it MUST disconnect the Network Connection to the Client as if
the network had failed.
If a Client does not receive a PINGRESP Packet within a reasonable amount of time after it has sent a PINGREQ,
it SHOULD close the Network Connection to the Server.
A Keep Alive value of zero (0) has the effect of turning off the keep alive mechanism.
This means that, in this case, the Server is not required to disconnect the Client on the grounds of inactivity.
Note that a Server is permitted to disconnect a Client that it determines to be inactive or non-responsive
at any time, regardless of the Keep Alive value provided by that Client.
The actual value of the Keep Alive is application specific; typically this is a few minutes.
The maximum value is 18 hours 12 minutes and 15 seconds.
The Keep Alive is a time interval measured in seconds. Expressed as a 16-bit word, it is the maximum time interval that is permitted to elapse between the point at which the Client finishes transmitting one Control Packet and the point it starts sending the next. It is the responsibility of the Client to ensure that the interval between Control Packets being sent does not exceed the Keep Alive value. In the absence of sending any other Control Packets, the Client MUST send a PINGREQ Packet.
The Client can send PINGREQ at any time, irrespective of the Keep Alive value, and use the PINGRESP to determine that the network and the Server are working.
If the Keep Alive value is non-zero and the Server does not receive a Control Packet from the Client within one and a half times the Keep Alive time period, it MUST disconnect the Network Connection to the Client as if the network had failed.
If a Client does not receive a PINGRESP Packet within a reasonable amount of time after it has sent a PINGREQ, it SHOULD close the Network Connection to the Server.
A Keep Alive value of zero (0) has the effect of turning off the keep alive mechanism. This means that, in this case, the Server is not required to disconnect the Client on the grounds of inactivity. Note that a Server is permitted to disconnect a Client that it determines to be inactive or non-responsive at any time, regardless of the Keep Alive value provided by that Client.
The actual value of the Keep Alive is application specific; typically this is a few minutes. The maximum value is 18 hours 12 minutes and 15 seconds.