Segment Routing Path Splitting for SDN Scalability
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Solution Overview
Problem
Software-defined networking (SDN) systems face scalability issues in implementing segment routing due to the limited number of labels supported by network elements, which restricts the use of segment identifiers (SIDs) for routing, especially in traffic-engineered networks where paths can have tens or hundreds of hops.
Innovation Solution
The SDN controller receives maximum SID depth values from network elements and splits paths into sub-paths based on these depths, allocating ordered SIDs to each network element within its maximum SID capacity, allowing packet forwarding along sub-paths to overcome the SID depth limitations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If segment routing is implemented in MPLS networks with limited label support (3-5 labels per node), then the number of SIDs that can be used for routing is restricted, but the need for routing arbitrarily long paths (tens or hundreds of hops) in traffic-engineered networks creates a contradiction between path length capability and SID depth limitation
Solution Approach 1:
The patent divides a long path into multiple sub-paths, where each sub-path's length is constrained by the maximum SID depth of network elements. The SDN controller calculates and provisions these sub-paths separately, allowing the overall path to extend beyond the SID depth limitation of individual nodes. This segmentation enables arbitrarily long paths while respecting the 3-5 label constraint at each node.
2Length of moving object
If the number of supported labels at each node is increased to support longer paths, then path length capability improves, but the device complexity and resource requirements increase
Solution Approach 1:
Instead of increasing the label stack capacity at each node, the patent segments the path into multiple sub-paths that fit within the existing 3-5 label constraint. This approach maintains device simplicity while achieving arbitrary path lengths through coordinated sub-path provisioning managed by the SDN controller.
Solution Approach 2:
The SDN controller acts as an intermediary that calculates and provisions multiple sub-paths between source and destination. It coordinates the routing across network elements with limited label stacks, enabling long paths without requiring any single node to support large label stacks. The controller manages the complexity centrally rather than distributing it across data plane devices.
Data Source
AI summary
Methods for segment routing in a software-defined networking (SDN) system are disclosed. In one embodiment, a method includes receiving a plurality of values of maximum segment identifier (SID) depths, each from one network element of the SDN system, and identifying a path for a packet to transmit through a plurality of network elements, where a plurality of SIDs corresponding to the plurality of network elements is ordered to represent the path. The method further includes splitting the path into a plurality of sub-paths based on the values of the maximum SID depths of the plurality of network elements, where each network element, for the path, is allocated to process a number of ordered SIDs, and where the number is within the network element's maximum SID depth, and causing packet forwarding of the packet along the plurality of sub-paths based on SIDs allocated to the network elements.