Dynamic Anti-Replay Table for Replay Detection in Delay Tolerant Networks
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Solution Overview
Problem
Existing solutions for detecting replayed data packets in Delay Tolerant Networks (DTNs) face challenges due to high processing power and memory requirements, leading to latency and risks of false or missed detections, especially when network link throughput and storage capacity are limited.
Innovation Solution
A method that uses a receiving station to read packet identifiers, consult a database of previously received identifiers, and update the database, employing anti-replay tables with shifting intervals and implicit storage to minimize memory usage and optimize packet verification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a sliding anti-replay table of fixed size storing the last N packets is used, then memory usage is limited, but detection precision deteriorates when network disruption causes packets to arrive out of order
Solution Approach 1:
The patent implements dynamic anti-replay tables with variable sizes instead of fixed-size tables. The head table and tail table can expand or contract based on the actual number of packets received and the disruption level in the network. This allows the system to maintain high detection precision by adjusting table sizes to match actual packet flow patterns while avoiding unnecessary memory consumption when disruption is minimal.
Solution Approach 2:
The system changes the parameter of table size dynamically based on network conditions. When packets arrive out of order due to network disruption, the tables expand to accommodate the larger range of sequence numbers. When network conditions are stable, the tables contract to minimize memory usage. This parameter adaptation resolves the contradiction between fixed memory limits and variable detection requirements.
2Measurement precision
If anti-replay tables are expanded to handle significant network disruption, then detection precision improves, but processing latency increases due to larger table manipulation
Solution Approach 1:
The patent divides the anti-replay table into two separate segments: a head table for storing recently received packet identifiers and a tail table for storing older identifiers. This segmentation allows independent management of each table, enabling faster operations on smaller sub-tables rather than manipulating one large table. The segmented structure reduces processing latency while maintaining the ability to detect replays across the full range of packet sequence numbers.
Solution Approach 2:
The system introduces a time-based dimension by separating the anti-replay table into head and tail tables based on the temporal order of packet arrival. This dimensional separation allows the system to handle out-of-order packets efficiently by directing them to appropriate tables, reducing the computational complexity of replay detection and lowering processing latency.
3Measurement precision
If two separate anti-replay tables (head table and tail table) are used to handle out-of-order packets, then detection precision improves, but device complexity increases
Solution Approach 1:
The patent merges the functionality of multiple anti-replay tables into a unified dual-table structure where the head table and tail table work together as an integrated system. Rather than implementing completely separate replay detection mechanisms, the invention combines them into a single coherent architecture with standardized operations, reducing overall system complexity while maintaining high detection precision.
Solution Approach 2:
The dual-table structure serves multiple functions: it handles in-order packets, out-of-order packets, packet retransmissions, and network disruption scenarios all within the same framework. This multi-functionality reduces the need for separate specialized mechanisms, thereby reducing device complexity while maintaining comprehensive replay detection capability.
4Measurement precision
If a database records all received packets for a very long time to detect replays in DTN, then detection precision improves, but memory capacity requirements increase substantially
Solution Approach 1:
The patent implements a mechanism where packet identifiers are discarded from the anti-replay tables after they have served their detection purpose. When the head table becomes full, its contents are transferred to the tail table, and the head table is cleared for new entries. This discarding and recovering approach allows the system to maintain long-term replay detection capability without permanently storing all packet identifiers, thereby reducing memory capacity requirements while preserving detection precision.
Data Source
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AI summary
A method for detecting whether a packet (11) from a plurality of packets transmitted by at least one transmitting station (E) across a network (3) has been replayed. Each packet comprises a message (M) and an identifier (SN), the plurality of packets being transmitted successively over several consecutive time periods. The method comprises the following steps: - reception by at least one receiving station (R) of the packet and reading of the identifier (SN) of the received packet to obtain a received identifier (SN), - consultation by the receiving station of a database (7) of identifiers that have already been received to determine whether the received identifier (SN) has already been received, and - if the received identifier has not already been received, updating the database including storing the received identifier. The identifier includes an indicator of membership in packet groups.The database includes one or more sub-tables (F) adapted for storing the identifiers of packets that have already been received, each sub-table being dedicated to one of the groups. The process further includes a database management step comprising the conditional deletion of any of the sub-tables if all the packets of the group to which that sub-table is dedicated have been received.