Segment Routing SID List Computation for Multipath Traffic Engineering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In computer networks, segment routing protocols face inefficiencies due to reliance on interior gateway protocols for shortest path routing, leading to incorrect packet forwarding and increased packet overhead, which can result in reduced network efficiency and unsupported SR-capable nodes.
Innovation Solution
Computational algorithms are used to minimize segment identifier (SID) lists by determining distances and candidate sets of network nodes or adjacencies based on routing metrics, generating SID lists that ensure packets follow specific multipaths within the network, thereby preventing incorrect forwarding and optimizing packet length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If segment routing relies on interior gateway protocols for shortest path routing, then routing simplicity is maintained, but packet forwarding accuracy deteriorates and network efficiency is reduced
Solution Approach 1:
The patent segments the routing control into two parts: IGP handles basic shortest path routing for simplicity, while a separate Segment Routing Policy (SRP) layer handles multipath steering for accuracy. This segmentation allows each layer to specialize - IGP maintains routing simplicity while SRP ensures packet forwarding accuracy by providing explicit path instructions through SID lists.
Solution Approach 2:
The patent introduces SID lists as an intermediary mechanism between IGP and the data plane. These SID lists act as mediators that carry explicit path steering instructions from the control plane to routers, allowing IGP to remain simple while ensuring accurate packet forwarding along intended multipaths.
2Reliability
If explicit path steering is implemented using SID lists, then packet forwarding accuracy is improved, but packet overhead increases
Solution Approach 1:
The patent applies partial action by including only the necessary SID list length to reach the egress router or multipath egress interface, rather than listing all intermediate nodes. This minimizes packet overhead while maintaining sufficient path steering information for accurate packet forwarding.
Solution Approach 2:
The patent changes the parameter of SID list length to be dynamically optimized based on network topology and policy requirements. By adjusting the SID list to contain only the minimum necessary segments for path steering, the patent reduces packet overhead while preserving forwarding accuracy.
3Productivity
If SID list length is reduced to minimize overhead, then network efficiency is improved, but support for SR-capable nodes may be limited
Solution Approach 1:
The patent makes the SID list structure universal by designing it to work with different SR-capable node types and configurations. The optimized SID list format can represent various path scenarios (single path, multipath, anycast) and work with different node capabilities, ensuring broad compatibility while maintaining network efficiency.
Solution Approach 2:
The patent adds a new dimension to SID list representation by using compressed formats and alternative encoding schemes that reduce length while preserving full expressiveness. This allows the SID list to convey the same routing information in a more compact form, supporting diverse SR-capable nodes without increasing overhead.
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
Techniques are described for computing lists of segment identifiers (SIDs) that satisfy each path in a multipath solution for a segment routing (SR) policy. In an example, a method includes obtaining, by a computing device, a plurality of paths through a network comprising one or more network nodes, each path of the plurality of paths representing a different sequence of links connecting pairs of the network nodes from a source to a destination; computing, by the computing device, one or more lists of segments identifiers (SIDs) that satisfy each path of the plurality of paths; and programming the network to forward network traffic based at least on the one or more lists of SIDs.