Browse Prior Art Database

Passive Keepalive Tuning with Short, Changing Windows

IP.com Disclosure Number: IPCOM000012468D
Original Publication Date: 2003-May-08
Included in the Prior Art Database: 2003-May-08
Document File: 2 page(s) / 8K

Publishing Venue

IBM

Abstract

A system is disclosed that enables a message sender to transmit messages to a passive receiver (one that does not respond with acknowledgements or other data) on a semi-regular cycle with high jitter, but imbues the receiver with the ability to detect the disappearance of the sender. Such a system is useful as a component in high-availability systems and using heartbeating (which implies hard real-time deadlines) on a computing platform that does not honor hard real-time deadlines. Examples of such platforms include non-realtime Unixes and Linux. This system enables detection of sender departure without active measures (eg., pinging or acknowledgement of receipt) on the part of the message receiver.

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Passive Keepalive Tuning with Short, Changing Windows

A system is disclosed that enables a message sender to transmit messages to a passive receiver (one that does not respond with acknowledgements or other data) on a semi-regular cycle with high jitter, where the receiver must detect the disappearance of the sender or a severed communications path without an active "are-you-there" protocol. The system is comprised of

a message sender;

a minimum waiting period between sends, known to the message sender;

a means of sending messages from the sender to the receiver (eg, tcp/ip

connection or datagram); a time series of observed times between message receipts, perhaps limited in

number, known to the message receiver; and a program component (a "time series analyzer") providing a timeout setting

based on the observed time series.

The system assumes the sender operates on a periodic cycle, sending messages approximately every Td seconds. This is the desiredwaiting period, but may be subject to delays and other types of perturbation. Optionally, the sender may communicate Td to the receiver in order to set its expectations appropriately. This provides protection against false detection of sender disappearance when Td is increasing.

The receiver operates by maintaining an estimate of the sender's current effective waiting period, which may be different from the sender's desired waiting period by a non-trivial amount, especially in non-realtime systems. The receiver expects the sender to be configured to send messages with a desired waiting period Td that is between Tmin and Tmax, with an initial desired waiting period also drawn from that range. The receiver uses its estimate...