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Hi all.  Many of us are familiar with the "my calls drop after xx min" type of support call.  Mostly killed off on HDX now with the TCP1720 keep alive.  What is the status of keep alive pulses for the RPG group?

There's an inference that in some environments RPG300s are dropping the connection consitently every 12.5 mins.  That does sound like a similar thing.

Pete

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The RealPresence Group Series system  sends a TCP Keep-Alive packet on the connection used for H.225.0 every 2 minutes. Same as newer HDX versions but  this setting is NOT user-configurable.

 

Some firewalls close down a TCP connection after a connection had not been used for a prolonged period of time (considered as "inactive" or "stale" connection). The TCP connection used for H.225.0 is typically only used at the very beginning of the call and the very end of the call. The purpose of the TCP Keep-Alive sent on the TCP connection used for H.225.0 is to keep the connection "active" so that a device on the intermediate network does not consider the connection stale and disconnect the TCP connection.

 

This TCP connection must continue to be "up" for the duration of the call. If a Polycom endpoint determines that the TCP connection used for H.225.0 had been terminated, the system will disconnect the H.323 call.

 

Below are some of the common scenarios where disconnection on the TCP connection used for H.225.0 disconnects an H.323 call.

 

SCENARIO 1: A device located on the intermediate network closes down the TCP port/connection. The device sends TCP RST or TCP FIN >>> This would cause the call to tear down immediately at that point.

 

SCENARIO 2: A device located on the intermediate network closes down the TCP port/connection. The device does not send TCP RST or TCP FIN >>> The call will stay up until the TCP Keep-Alive is sent on the connection.

(2A) When the TCP Keep-Alive packet is sent, the device will send TCP RST >>> The call will drop immediately at that point.

(2B) When the TCP Keep-Alive packet is sent, the device will ignore it >>> The endpoint will retransmit the Keep-Alive packet (via TCP retransmission) before eventually giving up and start tearing down the call.

 

SCENARIO 3: When an endpoint sends TCP Keep-Alive packet, a device on the intermediate network erroneously determines it as an illegal packet and sends TCP RST or TCP FIN on the connection >>> The call will drop immediately at that point.

 

For the general information regarding TCP Keep-Alives, see 4.2.3.6/RFC 1122.

 

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HP Recommended

The RealPresence Group Series system  sends a TCP Keep-Alive packet on the connection used for H.225.0 every 2 minutes. Same as newer HDX versions but  this setting is NOT user-configurable.

 

Some firewalls close down a TCP connection after a connection had not been used for a prolonged period of time (considered as "inactive" or "stale" connection). The TCP connection used for H.225.0 is typically only used at the very beginning of the call and the very end of the call. The purpose of the TCP Keep-Alive sent on the TCP connection used for H.225.0 is to keep the connection "active" so that a device on the intermediate network does not consider the connection stale and disconnect the TCP connection.

 

This TCP connection must continue to be "up" for the duration of the call. If a Polycom endpoint determines that the TCP connection used for H.225.0 had been terminated, the system will disconnect the H.323 call.

 

Below are some of the common scenarios where disconnection on the TCP connection used for H.225.0 disconnects an H.323 call.

 

SCENARIO 1: A device located on the intermediate network closes down the TCP port/connection. The device sends TCP RST or TCP FIN >>> This would cause the call to tear down immediately at that point.

 

SCENARIO 2: A device located on the intermediate network closes down the TCP port/connection. The device does not send TCP RST or TCP FIN >>> The call will stay up until the TCP Keep-Alive is sent on the connection.

(2A) When the TCP Keep-Alive packet is sent, the device will send TCP RST >>> The call will drop immediately at that point.

(2B) When the TCP Keep-Alive packet is sent, the device will ignore it >>> The endpoint will retransmit the Keep-Alive packet (via TCP retransmission) before eventually giving up and start tearing down the call.

 

SCENARIO 3: When an endpoint sends TCP Keep-Alive packet, a device on the intermediate network erroneously determines it as an illegal packet and sends TCP RST or TCP FIN on the connection >>> The call will drop immediately at that point.

 

For the general information regarding TCP Keep-Alives, see 4.2.3.6/RFC 1122.

 

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