Ordered Abstract Hops for Dynamic LSP Routing
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Solution Overview
Problem
Current routing protocols, such as RSVP-TE, face challenges in dynamically re-routing Label Switched Paths (LSPs) when constraints like link failures occur, as they are pinned to specific real hops, leading to network instability and manual intervention.
Innovation Solution
The introduction of abstract hops, which are logical containers of routers that satisfy logical combinations of link and node attributes, allows for dynamic re-routing by selecting alternative paths that meet the same abstract hop criteria, enabling flexible path constraints and automatic recovery from failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If RSVP-TE uses strict or loose hops as constraints for LSP setup, then the LSP can be established along a specified sequence of routers, but when any of the hops specified as constraint goes down or has its link capacity saturated, the LSP will no longer work and requires manual intervention
Solution Approach 1:
The patent introduces abstract hops as an intermediary layer between specific router hops and LSP constraints. Instead of directly constraining LSPs to specific router hops, the system uses abstract hops that represent logical groupings of routers sharing common attributes. This intermediary abstraction allows the LSP to automatically transition between member routers within the same abstract hop group, eliminating the need for manual reconfiguration when individual routers fail or become saturated.
2Adaptability or versatility
If RSVP-TE pins LSP to specific real hops, then the path can be precisely controlled, but the network resilience decreases when link failures occur
Solution Approach 1:
The patent segments the network into abstract hop groups based on shared attributes (administrative groups, SRLGs, geographic locations, etc.). Each abstract hop represents a segment containing multiple member routers that can serve as substitutes for one another. This segmentation allows the LSP to maintain its logical path structure while enabling dynamic substitution within segments, thus maintaining path control flexibility while improving network resilience against failures.
Solution Approach 2:
The patent changes the parameter representation from specific router identifiers to abstract attribute-based groupings. Instead of constraining LSPs by fixed router hop sequences, the system constrains them by abstract hops defined through parameters such as administrative groups, SRLGs, and other network attributes. This parameter transformation enables the LSP to adapt to failures by transitioning between routers that share the same attribute parameters, thereby improving reliability while preserving controlled path selection.
3Measurement precision
If administrators configure specific hops for LSP constraints, then the path selection is precise, but the system lacks flexibility for automatic recovery
Solution Approach 1:
The patent introduces abstract hops as an intermediary that bridges precise path constraints and automatic recovery. The abstract hop acts as a mediator that translates specific router hop requirements into attribute-based logical groupings. This intermediary layer maintains the precision of path constraints through attribute definitions while simultaneously enabling automatic recovery by allowing the system to dynamically select any member router within the abstract hop group without requiring administrator intervention.
Data Source
AI summary
A network device receives configuration information defining one or more abstract hops for which membership is defined as those network devices that satisfy a logical combination of one or more constituent attributes. The network device determines based on network topology information, for each of the defined abstract hops, a set of network devices that qualify for membership in the abstract hop. The network device receives a request to establish a label switched path (LSP) from an ingress network device to an egress network device, wherein the request specifies, as a constraint for the LSP, a plurality of hops in a defined order, including the one or more abstract hops. The network device selects a path from the ingress network device to the specified egress network device based on the ordered abstract hop constraint, and establishes the LSP along the selected path according to the defined order of the request.