Globally Synchronized Timestamp Counter for Packet Processing
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Solution Overview
Problem
Existing distributed packet processing systems lack a reliable mechanism for globally synchronized timestamps, which is crucial for accurate latency measurement, packet header regeneration, and secure data transmission, especially in systems like ROHC and encrypted DirectTV signals, due to limitations in time synchronization across multiple processing nodes.
Innovation Solution
A system where a master card with a clock source and counter transmits counter value information on two bus lines periodically, with each card authenticating parity to ensure synchronization, and if errors occur, the software switches to the second bus line and notifies the chassis, maintaining synchronization across all cards in the chassis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single bus line is used for transmitting counter value information, then the system complexity is reduced, but the reliability of timestamp synchronization deteriorates due to potential transmission errors
Solution Approach 1:
The patent applies local quality by creating two separate bus lines (first bus line and second bus line) with different physical paths between the master card and slave cards. This allows each bus line to have independent transmission characteristics, so that if one line experiences interference or errors, the other line remains unaffected and can continue providing reliable timestamp synchronization.
Solution Approach 2:
The patent implements beforehand cushioning by pre-configuring dual bus lines and parity check mechanisms before transmission errors can occur. The system proactively establishes redundant communication paths and error detection capabilities, allowing it to switch to the second bus line if the first bus line experiences parity errors, thus preventing synchronization failures before they impact system operation.
2Reliability
If parity authentication is implemented on received counter value information, then the reliability of timestamp data is improved, but the processing time and computational overhead increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and attaching parity information to counter value data before transmission. The master card computes the parity of the counter value and transmits it along with the counter value itself. Slave cards then perform rapid parity verification by comparing the received parity with locally computed parity, enabling fast error detection without requiring complex post-reception processing.
3Reliability
If the system switches to the second bus line when parity errors occur, then the reliability of timestamp synchronization is maintained, but the system complexity and software overhead increase
Solution Approach 1:
The patent implements feedback by continuously monitoring the integrity of received counter value information through parity authentication. When a slave card detects a parity error on the first bus line, it immediately feeds back this error condition and switches to receiving counter value information from the second bus line. This closed-loop error detection and correction mechanism maintains synchronization reliability while using straightforward switching logic.
Data Source
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AI summary
The present invention relates to a synchronized timestamp mechanism in a packet processing system. This synchronized timestamp mechanism provides a globally synchronized counter value so counters located on separate packet processing cards can be synchronized. The synchronizing of these packet processing cards provides tracking of how long it takes for packets to be processed, provides the ability to generate packet headers that include sequence numbers for robust header compression, and allows the use of encryption protocols without a time reference signal. The synchronization is provided by sending the cards with counter value information and this information can be used to update the card's internal counter value information so that the card is synchronized with other cards.