Segment Routing Label Forwarding Table Construction
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Solution Overview
Problem
The deployment of typical service bearer networks is complex due to multiple routing protocols, and they require static RSVP configurations, leading to high resource consumption and inefficiencies, particularly in handling bandwidth and traffic engineering, which Segment Routing aims to address by using source-based routing with Segment Routing Global Blocks (SRGBs) but faces challenges with very long segment information causing hardware upgrades and MTU issues.
Innovation Solution
A method where nodes receive a segment list and segment list ID to construct a label forwarding table, allowing for efficient packet forwarding without the need for hardware upgrades, by maintaining a mapping relationship between the segment list and ID, and using global labels as index offsets within the SRGB domain, thereby reducing the depth of the label stack and addressing load efficiency and MTU problems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If segment information is extended to support very long paths, then routing flexibility and network coverage are improved, but label stack depth increases requiring hardware upgrades
Solution Approach 1:
The patent segments the label stack into two parts: a compressed segment list (carried in the packet header) and a local forwarding table (stored in each router). This segmentation allows the routing information to be distributed between packet data and router memory, reducing the need for deep label stacks in hardware while maintaining full routing flexibility.
Solution Approach 2:
The patent moves the label stack from a purely in-packet representation to a two-dimensional structure combining packet header fields and router forwarding tables. This dimensional change allows routing information to be accessed from both the packet data and the router's local table, effectively reducing the depth requirement of the label stack in hardware.
2Adaptability or versatility
If segment information is extended to support very long paths, then network coverage is improved, but packet size increases causing MTU problems
Solution Approach 1:
The patent extracts the detailed segment list from the packet body and stores it in the router's local forwarding table. Only a compact identifier (segment list ID) remains in the packet header, significantly reducing packet size while preserving the ability to represent very long paths through the router's stored segment information.
Solution Approach 2:
The patent creates a copy of the segment list in the router's forwarding table, allowing the packet to carry only a reference (segment list ID) rather than the full segment information. This copying mechanism enables long path representation without increasing packet size, as the detailed information resides in the router's memory.
3Ease of operation
If traditional destination-based forwarding is used, then forwarding simplicity is maintained, but dynamic source-based routing and traffic engineering are not supported
Solution Approach 1:
The patent creates a universal forwarding mechanism that handles both traditional destination-based routing and source-based segment routing through a single label forwarding table structure. The table can accommodate both destination prefixes and segment list identifiers, allowing the same forwarding infrastructure to support multiple routing paradigms without sacrificing simplicity or flexibility.
Data Source
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AI summary
Methods and devices for constructing a label and forwarding a label packet are provided. A node receives a message which carries a segment list and a segment list Identifier (ID) for identifying the segment list. The node constructs a label forwarding table according to the segment list and the segment list ID, and performs forwarding according to the label forwarding table; and/or the node maintains a mapping relationship between the segment list and the segment list ID. The solution solves a problem of needing to upgrade forwarding plane hardware to support a greater label stack processing capacity, and a problem of load efficiency and a Maximum Transmission Unit (MTU) problem, which exist in the related technology, thereby achieving effects of lowering the requirement for the label stack processing capacity of the forwarding plane hardware, and effectively solving the problem of load efficiency and the MTU problem.