Cross-Layer Path Establishment in Optical Networks
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Solution Overview
Problem
In automatically switched optical networks, the delay in path computation and establishment across IP and optical layers can result in unsuccessful path establishment or failure to meet bandwidth requirements due to occupied or inadequately provisioned bottom-layer paths.
Innovation Solution
A cross-layer path establishment method where an upper-layer PCE determines and acquires an established lower-layer path that meets the required bandwidth, allowing the upper-layer first node to directly use this path for establishing the complete LSP, thereby avoiding the need to re-establish a bottom-layer path and ensuring it meets the bandwidth requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the optical-layer PCE computes the bottom-layer path after the IP-layer PCE requests it, then the path computation can be completed, but the delay causes the bottom-layer path to be occupied by another service or have inadequate bandwidth
Solution Approach 1:
The patent applies preliminary action by having the optical-layer PCE proactively compute and establish bottom-layer paths before the IP-layer PCE needs them. The optical-layer PCE continuously monitors network state and pre-establishes paths that may be needed by upper layers, eliminating the delay caused by reactive path computation. This ensures the bottom-layer path is ready and available when the IP-layer PCE requests it, preventing occupation by other services or bandwidth insufficiency.
2Ease of operation
If the IP-layer first node establishes the complete path using signaling protocol, then the path can be set up, but the bottom-layer path may already be occupied or have inadequate bandwidth causing establishment failure
Solution Approach 1:
The patent implements feedback by establishing continuous information exchange between the IP-layer PCE and optical-layer PCE. The optical-layer PCE provides real-time feedback about the state of bottom-layer paths, including bandwidth availability and occupation status. This feedback mechanism allows the IP-layer PCE to make informed decisions about path establishment, selecting only those paths that are guaranteed to meet bandwidth requirements and are not occupied by other services.
3Adaptability or versatility
If separate PCEs are configured for IP network and optical network, then each layer can compute paths independently, but cross-layer path establishment becomes complex and delayed
Solution Approach 1:
The patent applies the nested doll principle by creating a hierarchical relationship where the IP-layer PCE and optical-layer PCE are nested within a unified path computation framework. The optical-layer PCE operates as a subordinate entity to the IP-layer PCE, with the ability to independently compute bottom-layer paths while receiving guidance from and providing information to the upper layer. This nested structure allows independent computation at each layer while maintaining tight coordination, reducing overall system complexity.
Data Source
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AI summary
Embodiments of the present invention relate to the field of communications, and disclose a cross-layer path establishment method and apparatus, resolving a problem in the prior art that path establishment fails or an established path cannot meet a bandwidth requirement due to a delay in a process from computing a path by a lower-layer PCE to completing establishment of the path crossing an upper-layer and a lower-layer. A specific solution is: determining, by an upper-layer PCE, upper-layer path information of a to-be-established LSP, an identifier of a first node of a lower-layer path, and an identifier of a last node of the lower-layer path according to an identifier of an upper-layer first node, an identifier of an upper-layer last node, and a bandwidth requirement of the to-be-established label switched path LSP; acquiring an identifier of an established lower-layer path that matches the identifier of the first node of the lower-layer path, the identifier of the last node of the lower-layer path, and the bandwidth requirement; and sending, to the upper-layer first node, a path establishment indication that includes the upper-layer path information and the identifier of the lower-layer path, so that the upper-layer first node establishes the to-be-established LSP according to the upper-layer path information and the identifier of the lower-layer path. The present invention is used in a process of establishing a path that crosses an upper-layer and a lower-layer.