SCTP Association Discovery via Verification Tag Tracking
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Solution Overview
Problem
Monitoring SCTP associations in a network is challenging due to the difficulty in correlating SCTP packets to their proper association, especially when multiple IP addresses are used over the life of the association, making it hard for network monitoring systems to track and measure communication links with multihoming features.
Innovation Solution
The method involves monitoring packets to determine the combination of source and destination IP addresses and port numbers that define an association, resolving verification tags, and using these tags to identify subsequent packets belonging to the association, even if IP addresses or port numbers change, allowing continuous monitoring and measurement of communication links.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SCTP multihoming is used to increase reliability, then connection reliability is improved, but packet correlation difficulty increases
Solution Approach 1:
The patent extracts and stores the verification tag from SCTP packets during the initial association setup phase, before multihoming occurs. This preliminary extraction allows the monitoring system to have the correlation key ready in advance, eliminating the need to track multiple IP address combinations during runtime.
Solution Approach 2:
The verification tag serves as an intermediary identifier that mediates between the multiple IP addresses and the association. Instead of directly correlating packets based on source/destination IP pairs (which change in multihoming), the system uses the verification tag as a stable intermediate key to identify the association.
2Adaptability or versatility
If multiple IP addresses are used during association life, then multihoming support is improved, but association tracking complexity increases
Solution Approach 1:
The patent extracts the verification tag from the SCTP packet header and separates it from the IP address information. By taking out this stable identifier and storing it independently in an data structure, the system eliminates the complexity of tracking multiple IP address combinations while maintaining multihoming support.
Solution Approach 2:
The system changes the correlation parameter from dynamic IP address pairs to a static verification tag. This parameter change transforms the tracking mechanism from one that must adapt to changing IP addresses to one that uses a constant identifier throughout the association lifecycle.
3Duration of action of moving object
If monitoring starts after association setup, then late-joining monitoring is enabled, but initial packet correlation is lost
Solution Approach 1:
The system performs preliminary extraction of the verification tag from SCTP packets during the initial association setup, storing it in an data structure before monitoring officially begins. This ensures that when monitoring starts, the correlation key is already captured and can be used to identify subsequent packets.
Solution Approach 2:
The verification tag extraction and storage mechanism ensures continuous associability of packets throughout the entire association lifecycle, from setup through teardown. By maintaining the verification tag in the data structure throughout, the system enables uninterrupted monitoring and measurement of the communication link.
Data Source
AI summary
Systems and methods for discovering SCTP associations between devices communicating in a network are described. A method comprises monitoring packets communicated among a plurality of source and destination devices, determining a combination of source EP address, source port number, destination IP address, and destination port number that defines an association between a source device and a destination device, and resolving a combination of source and destination verification tags that further defines the association based upon the combination of EP addresses and port numbers. The method further comprises ascertaining whether a subsequently monitored packet belongs to the association based at least in part upon an element of the combination of verification tags after at least one element of the combination of EP addresses and port numbers has changed during the ongoing communication.