Segmented LSP Ping for Segment Routing Traffic Engineering
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Solution Overview
Problem
In large-scale computer networks using segment routing, existing LSP ping mechanisms send echo request packets to every router along the path, including non-participating devices, leading to increased network load and inefficiency in detecting data plane failures.
Innovation Solution
An enhanced LSP ping mechanism where an ingress router selectively pings only the devices identified in the forwarding equivalence class (FEC) stack, sending MPLS echo request packets to each device in the stack and updating the stack upon receiving responses, thereby reducing unnecessary network traffic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the LSP ping mechanism sends echo request packets to every router along the path, then comprehensive connectivity verification is achieved, but network load increases due to responses from non-participating devices
Solution Approach 1:
The patent segments the LSP path into distinct segments based on the FEC stack, where each segment corresponds to a participating device. Instead of treating the entire path uniformly, the mechanism divides it into manageable segments that can be independently verified, allowing the system to target only relevant devices for ping operations.
Solution Approach 2:
The patent extracts only the necessary participating devices from the complete LSP path by utilizing the FEC stack information. By taking out only the devices that actually participate in the segment routing (those present in the FEC stack) and excluding non-participating devices, the mechanism reduces unnecessary ping operations and corresponding network load.
2Measurement precision
If the LSP ping mechanism pings every router along the path, then complete fault isolation is achieved, but detection efficiency decreases due to processing responses from all devices
Solution Approach 1:
The patent segments the fault isolation process into discrete steps corresponding to each FEC entry. By dividing the verification process into segments that target specific participating devices sequentially, the mechanism maintains precise fault location capability while reducing the overall number of devices that need to be probed.
Solution Approach 2:
The patent applies partial action by pinging only the necessary subset of devices (those in the FEC stack) rather than all devices along the path. This partial verification approach is sufficient for achieving complete fault isolation accuracy while significantly improving detection efficiency by avoiding unnecessary pings of non-participating devices.
3Length of stationary object
If the LSP ping mechanism sends packets to all next hop routers, then complete path coverage is achieved, but network traffic increases with unnecessary responses
Solution Approach 1:
The patent extracts the essential participating devices from the complete next-hop router list by referencing the FEC stack. This extraction process identifies which next-hop routers actually participate in the segment routing and should receive ping packets, filtering out non-participating devices that would generate unnecessary traffic.
Solution Approach 2:
The FEC stack serves multiple functions: it defines the segment routing path, identifies participating devices, and guides the ping operations. This multi-functionality allows the mechanism to achieve complete path coverage verification while using a single data structure to control traffic generation, avoiding redundant packets.
Data Source
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AI summary
Techniques are described for selectively pinging certain devices along a segment routing label switched path (LSP) to detect failures in the segment routing LSP. For example, an ingress device comprises one or more processors operably coupled to a memory that are configured to: in response to a request to verify connectivity of a segment routing LSP, configure a FEC stack specifying a stack of segment routing labels for the segment routing LSP; for each of the one or more devices identified from the FEC stack: generate a respective MPLS connectivity request packet for a respective device identified from an outermost FEC of the FEC stack; send the MPLS connectivity request packet to the respective device; receive an MPLS connectivity response packet that verifies connectivity of the respective device; and in response, update the FEC stack by removing the outermost FEC of the FEC stack that identifies the respective device.