Stateful PCEP Extensions for MPLS TE LSP Management
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Solution Overview
Problem
Constraint-based path computation in large, multi-domain, multi-region, and/or multi-layer networks is complex due to insufficient traffic engineering information exchange between administrative domains, limiting the ability to compute optimal paths for Multi-Protocol Label Switching (MPLS) Traffic Engineering Label Switched Paths (TE LSPs).
Innovation Solution
The extension of the Path Computation Element (PCE) communication protocol (PCEP) to support messages that enable PCEs to actively modify TE LSPs by receiving LSP state information, assuming control, and injecting state into network routers, providing continuous visibility and control over LSP parameters like bandwidth and status, allowing for synchronized resource demand placement across network routers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If constraint-based path computation is performed in large, multi-domain, multi-region, and/or multi-layer networks, then path optimization capability is improved, but system complexity increases due to insufficient traffic engineering information exchange between administrative domains
Solution Approach 1:
The patent introduces a stateful Path Computation Element (PCE) as an intermediary that centralizes path computation functionality. The PCE receives path computation requests from Path Computation Clients (PCCs), maintains state information about TE LSPs, and returns computed paths. This mediator approach consolidates the complex constraint-based path computation logic in a centralized entity rather than distributing it across multiple network devices, thereby improving path optimization capability while managing system complexity through centralized control.
Solution Approach 2:
The patent implements a feedback mechanism where the stateful PCE maintains continuous state information about TE LSPs including bandwidth, status, and other parameters. The PCE uses this maintained state information to make informed path computation decisions and provides updates to PCCs. This feedback loop enables the system to adapt to changing network conditions and optimize paths dynamically while managing complexity through structured information exchange protocols.
2Measurement precision
If a stateful PCE maintains state for TE LSPs to enable sophisticated path computation, then path computation accuracy is improved, but information exchange requirements between PCE and PCCs increase
Solution Approach 1:
The patent extends the PCEP protocol to serve multiple functions: it carries path computation requests, returns computed paths, exchanges LSP state information (bandwidth, status, parameters), and enables PCE control over PCC behavior. This multi-functional protocol design consolidates various information exchange requirements into a single standardized interface, reducing the need for multiple separate communication channels and minimizing information loss through comprehensive state tracking.
Solution Approach 2:
The stateful PCE continuously maintains and updates state information about TE LSPs, including bandwidth availability, LSP status, and other parameters. This maintained state information is fed back to PCCs through extended PCEP messages, enabling accurate path computation decisions. The feedback mechanism ensures that the PCE has up-to-date information for accurate computation while structuring the information exchange to minimize losses through standardized message formats.
3Productivity
If PCEP is extended to support active PCE control of TE LSPs, then resource management capability is improved, but protocol complexity increases
Solution Approach 1:
The patent enables the PCE to proactively send control messages to PCCs to modify TE LSP parameters, trigger path re-computation, or adjust resource allocations before network conditions deteriorate. This preliminary action capability allows the PCE to optimize resource management by anticipating needs and making adjustments in advance, improving productivity while managing protocol complexity through structured message types that encode multiple control functions.
Solution Approach 2:
The extended PCEP protocol implements multi-functional messages that can carry path computation requests, state information exchange, control instructions, and acknowledgments within a unified framework. This universal message structure handles multiple resource management tasks through standardized extensions rather than requiring separate protocols for each function, thereby improving resource management capability while controlling protocol complexity through systematic design.
Data Source
AI summary
In general, techniques are described for extending a path computation element (PCE) communication protocol (PCEP) to support messages that enable PCEs to actively modify Multi-Protocol Label Switching (MPLS) for Traffic Engineering Label Switched Paths (TE LSPs) in and across network domains. In one example, an LSP database of a router includes configuration data for one or more LSPs configured in the router and further includes LSP state information specifying a current state of all LSPs of the router. A path computation client (PCC) of a router establishes an extended PCEP session and synchronizes LSP state information to a stateful PCE using the extended PCEP session. Subsequently, the stateful PCE sends an LSP update request to the PCC in the extended PCEP session, wherein the LSP update request includes one or more updated parameters for the LSP. The PCC then re-signals the LSP through the network according to the updated parameters.