Automated Bi-directional LSP Setup in MPLS Networks
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Solution Overview
Problem
Establishing bi-directional label switched paths in MPLS networks is cumbersome due to the need for manual setup of separate unidirectional LSPs, which increases administrative complexity and the likelihood of communication interruptions, as the path of the return LSP is not known until the forward LSP is set up.
Innovation Solution
A method and system for automatically establishing a complementary label switched path by sending a first LSP setup request message with a bi-directional indicator, triggering a second LSP setup request message from the receiving device, ensuring both unidirectional LSPs follow the same path, using RSVP PATH and RESV messages with opaque objects to signal resource requirements and association.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If manual setup of separate unidirectional LSPs is used, then bi-directional communication can be established, but administrative complexity increases and the likelihood of communication interruptions increases
Solution Approach 1:
The patent combines the setup procedures for forward and return LSPs into a single automated operation. When an administrator initiates an LSP setup, the system automatically establishes both the forward LSP (ingress to egress) and the return LSP (egress to ingress) using the same path parameters, eliminating the need for separate manual configurations and reducing administrative complexity while ensuring path consistency for reliable bi-directional communication
Solution Approach 2:
The system enables self-service by allowing the LSP setup mechanism to automatically generate and configure the return path without human intervention. The ingress LER receives a setup request, determines the optimal path, and automatically provisions both forward and return LSPs with matching path characteristics, making the system self-configuring and reducing reliance on manual administrative actions
2Reliability
If the return LSP path is determined after the forward LSP is set up, then the forward LSP can be established, but the return LSP may take a different path increasing communication interruption risk
Solution Approach 1:
The patent applies preliminary action by determining the return LSP path at the same time as the forward LSP path during the initial setup phase. The ingress LER calculates both paths simultaneously using the same routing criteria and path selection algorithms, ensuring they traverse identical network segments before any traffic is routed, thereby eliminating path mismatches and communication interruptions while avoiding sequential determination delays
3Adaptability or versatility
If two separate LSP setup procedures are used for bi-directional communication, then flexibility in path selection is maintained, but the burden on administrators increases
Solution Approach 1:
The system implements self-service by automatically performing the entire bi-directional LSP setup process including path calculation, resource reservation, and configuration synchronization. The administrator simply initiates a single setup request, and the system autonomously provisions both forward and return LSPs with consistent path selection, maintaining flexibility through automated path optimization while dramatically improving ease of operation by eliminating complex manual procedures
Data Source
AI summary
A method and apparatus for unilaterally forming a bi-directional label switched path between first and second routing devices in a network is disclosed. The method of the preferred embodiment is comprised of the steps of: sending a first LSP path message comprising a first bi-directional indicator from the first routing device to the second routing device; and automatically sending a second LSP path message from the second routing device to the first routing device in response to the first bi-directional indicator. The resulting two unidirectional label switched paths may be associated with one another at the endpoints to form a bi-directional LSP. The bi-directional indicator is preferably an RSVP protocol opaque object used in part to specify the router resources required for the return LSP, which may be different than the resource requirements of the forward LSP specified in the first LSP path message.