MRP timers
MRP uses the following timers to control message transmission.
Periodic timer
The Periodic timer controls the transmission of MRP messages. An MRP participant starts its own Periodic timer upon startup, and stores MRP messages to be sent before the Periodic timer expires. When the Periodic timer expires, MRP sends stored MRP messages in as few MRP frames as possible and restarts the Periodic timer. This mechanism reduces the number of MRP frames periodically sent.
You can enable or disable the Periodic timer. When the Periodic timer is disabled, MRP does not periodically send MRP messages. Instead, an MRP participant sends MRP messages when the LeaveAll timer expires or the participant receives a LeaveAll message from the peer participant.
Join timer
The Join timer controls the transmission of Join messages. An MRP participant starts the Join timer after sending a Join message to the peer participant. Before the Join timer expires, the participant does not resend the Join message when the following conditions exist:
The participant receives a JoinIn message from the peer participant.
The received JoinIn message has the same attributes as the sent Join message.
When both the Join timer and the Periodic timer expire, the participant resends the Join message.
Leave timer
The Leave timer controls the deregistration of attributes.
An MRP participant starts the Leave timer in one of the following conditions:
The participant receives a Leave message from its peer participant.
The participant receives or sends a LeaveAll message.
The MRP participant does not deregister the attributes in the Leave or LeaveAll message if the following conditions exist:
The participant receives a Join message before the Leave timer expires.
The Join message includes the attributes that have been encapsulated in the Leave or LeaveAll message.
If the participant does not receive a Join message for these attributes before the Leave timer expires, MRP deregisters the attributes.
LeaveAll timer
After startup, an MRP participant starts its own LeaveAll timer. When the LeaveAll timer expires, the MRP participant sends out a LeaveAll message and restarts the LeaveAll timer.
Upon receiving the LeaveAll message, other participants restart their LeaveAll timer. The value of the LeaveAll timer is randomly selected between the LeaveAll timer and 1.5 times the LeaveAll timer. This mechanism provides the following benefits:
Effectively reduces the number of LeaveAll messages in the network.
Prevents the LeaveAll timer of a particular participant from always expiring first.