Out-of-Resources Reporting via TLV Flags in Data Networks
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Solution Overview
Problem
Current methods for reporting out-of-resources (OOR) conditions in data networks, such as advertising entities as having a maximum cost, are imprecise and can disrupt existing data flows by causing unnecessary path recalculations and fail to distinguish between DS-TE classes that can or cannot use the entity.
Innovation Solution
Generating and broadcasting advertisement messages with type-length-value (TLV) objects that specifically report OOR conditions for entities like nodes, line cards, and data links, allowing head-end nodes to determine paths that avoid resource-constrained entities without recalculating existing LSPs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If advertisement messages use maximum cost to indicate OOR conditions, then OOR conditions can be reported, but existing data flows are disrupted due to unnecessary path recalculations
Solution Approach 1:
The patent segments the OOR condition reporting by introducing separate flag fields for different OOR scenarios (permanent OOR vs. temporary OOR). This allows head-end nodes to distinguish between conditions requiring path recalculation and those that don't, thereby maintaining data flow continuity while reporting OOR conditions precisely.
Solution Approach 2:
The patent changes the parameter representation by using specific flag bits (e.g., permanent OOR flag, temporary OOR flag) within the advertisement messages to encode different OOR states. This enables precise condition reporting without triggering unnecessary path recalculations, as nodes can interpret the specific flag values to determine appropriate actions.
2Loss of information
If advertisement messages report OOR conditions for all DS-TE classes, then complete resource information is provided, but message complexity increases
Solution Approach 1:
The patent applies partial action by reporting OOR conditions selectively - only for DS-TE classes that actually experience resource constraints. The flag fields are set only when specific OOR conditions exist, avoiding the need to report all possible classes and reducing message complexity while maintaining information completeness for affected classes.
Solution Approach 2:
The patent segments the resource information reporting by using separate flag fields for different DS-TE classes and OOR types. This segmentation allows the advertisement messages to include only relevant information for each class, reducing overall message complexity while maintaining complete information for classes that need it.
3Reliability
If head-end nodes recalculate paths for existing LSPs when receiving OOR advertisements, then paths can avoid resource-constrained entities, but data flow disruption occurs
Solution Approach 1:
The patent uses parameter changes in the form of specific flag values (permanent OOR flag vs. temporary OOR flag) to indicate different levels of path recalculation urgency. Head-end nodes can interpret these parameter values to determine whether to recalculate paths immediately or wait, thus maintaining path validity while minimizing data flow disruption.
Solution Approach 2:
The patent introduces dynamic behavior by allowing different response strategies based on the OOR condition type. For temporary OOR conditions, nodes can dynamically choose to wait and observe whether the condition resolves before recalculating paths, whereas permanent OOR conditions trigger immediate path recalculation. This dynamic approach maintains reliability while preserving data flow continuity.
Data Source
AI summary
A system and method for advertising out-of-resources (OOR) conditions for entities, such as nodes, line cards and data links, in a manner that does not involve using a maximum cost to indicate the entity is “out-of-resources.” According to the technique, an OOR condition for an entity is advertised in one or more type-length-value (TLV) objects contained in an advertisement message. The advertisement message is flooded to nodes on a data network to inform them of the entity's OOR condition. Head-end nodes that process the advertisement message may use information contained in the TLV object to determine a path for a new label switched path (LSP) that does not include the entity associated with the OOR condition.