Segment Routing MPLS Packet Forwarding With Adaptive Label Stacks
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Solution Overview
Problem
In segment routing-based MPLS networks, the label stack size processed by each node may vary, leading to potential forwarding errors when the ingress node generates a label stack exceeding the maximum size processable by intermediate nodes, resulting in packets not being delivered to the final destination.
Innovation Solution
The method involves checking the label stack size at each node along the forwarding path and generating either a first MPLS packet with a standard label stack or a second MPLS packet with an extension header and partial label stack based on the node's processable size, ensuring error-free forwarding by adapting the packet format accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ingress node generates a label stack with maximum size to accommodate all intermediate nodes, then the packet forwarding completeness is improved, but the compatibility with intermediate nodes having limited processing capacity deteriorates
Solution Approach 1:
The label stack is segmented into two parts: an extension header containing the full label stack information, and an MPLS header containing only the portion that intermediate nodes can process. This segmentation allows the system to maintain both completeness of routing information and compatibility with limited processing capacity of intermediate nodes.
Solution Approach 2:
The extension header acts as an intermediary that carries the complete label stack information while the MPLS header provides the processed form that intermediate nodes can handle. This intermediary structure enables seamless interaction between the ingress node's comprehensive routing information and intermediate nodes' processing limitations.
2Device complexity
If the ingress node uses a unified label stack format for all nodes, then the simplicity of packet format is improved, but the adaptability to different node processing capacities deteriorates
Solution Approach 1:
The packet format dynamically adapts based on the processing capacity of intermediate nodes. The system selects between two formats: a standard MPLS header format when nodes have sufficient capacity, and an extended format with extension header when nodes have limited capacity. This dynamic adaptation maintains simplicity where possible while providing necessary adaptability.
Solution Approach 2:
Different parts of the packet header have different structures tailored to specific needs. The extension header contains complete labeling information for nodes that need it, while the MPLS header provides optimized processing for nodes with standard capacity. This local differentiation allows each node type to process packets in the most efficient way for its capabilities.
3Manufacturing precision
If the ingress node checks label stack size at each intermediate node, then the forwarding accuracy is improved, but the processing time and complexity deteriorates
Solution Approach 1:
The ingress node performs preliminary checking of intermediate nodes' label stack processing capacities before generating the packet. This advance verification allows the ingress node to pre-determine the appropriate packet format (standard or extended) and avoid unnecessary processing delays at intermediate nodes, thereby improving forwarding accuracy without significant time loss.
Data Source
AI summary
A segment routing-based MPLS packet forwarding method and a device thereof are proposed. The method includes establishing a forwarding path in a Multiple Protocol Label Switching (MPLS) network by receiving a packet, checking whether processing of a size of a label stack related to each node included in the forwarding path is available or not in each node, generating a first MPLS packet by adding an MPLS header having the label stack to the packet in response to availability of the processing, and generating a second MPLS packet by adding an extension header having the label stack and by adding an MPLS header having a part of the label stack allocated according to the label stack size processable by each node to the packet in response to unavailability of the processing.