Route Tracing Program for TOS Field Modification Detection
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Solution Overview
Problem
Conventional network monitoring and analysis systems fail to accurately identify specific network elements that modify the Type of Service (TOS) field in IP headers during VoIP communications, leading to interference with IP telephony due to inappropriate remarking, especially in long and complex network paths.
Innovation Solution
A modified route tracing program that sends messages with increasing time-to-live values and a designated TOS value to detect network elements that modify the TOS field by monitoring changes in time exceeded messages, allowing for the identification of specific network elements performing TOS remarking and generating a visual display of these elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sniffers are used at source and destination network elements to detect TOS field changes, then TOS field modification can be detected, but the particular network element making the modification cannot be identified
Solution Approach 1:
The patent segments the network path into individual hops and uses route tracing messages with incrementing time-to-live values to probe each segment separately. This allows identification of which specific network element (segment) is making the TOS modification, rather than only detecting that a modification occurred somewhere in the path.
Solution Approach 2:
The patent introduces route tracing messages as an intermediary tool that carries TOS field information through the network path. These messages interact with each network element along the path, allowing the source element to observe how the TOS field changes at each hop and identify the specific element causing the change.
2Reliability
If conventional traceroute programs are used to show destination unreachable for particular TOS value, then routing issues can be detected, but the program exits without identifying the particular network element performing TOS remarking
Solution Approach 1:
The patent performs preliminary probing of each network element along the path using route tracing messages before concluding that a destination is unreachable. By incrementing the time-to-live value and observing responses from each hop, the system identifies which specific element is remarking the TOS field, providing actionable troubleshooting information rather than simply exiting when a destination appears unreachable.
3Adaptability or versatility
If network paths are made long and span large geographic areas to connect source and destination, then network coverage is improved, but the ability to locate particular network elements performing TOS remarking becomes more difficult
Solution Approach 1:
The patent divides the long network path into discrete segments corresponding to individual network elements. By sending route tracing messages with incrementing time-to-live values, each message reaches only a specific segment (network element), allowing systematic identification of which element along the extended path is performing TOS remarking.
Solution Approach 2:
The patent sends multiple route tracing messages with progressively increasing time-to-live values, performing more probing actions than a simple end-to-end check. This excessive action of probing each intermediate element ensures that even in long paths spanning large geographic areas, the specific element making TOS modifications can be located.
Data Source
AI summary
One or more network elements that modify type of service values in a network are detected by sending route tracing messages having increasing time-to-live values and a designated type of service value from a first network element to a second network element. Type of service values are monitored in respective time exceeded messages received from respective network elements on a given network path between the first network element and the second network element responsive to the route tracing messages. At least a particular one of the network elements on the given network path that has made a modification in type of service value relative to the designated type of service value is identified, based on the monitored type of service values in the respective time exceeded messages.