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Containerized PCE
Containerized Path Computation Element (cPCE) is a light-weight micro-services based containerized Path Computation Engine application that can be deployed on or off box. Compute Off-load is a Traffic Engineering (TE) use-case where the computation of TE-Paths is off-loaded by the head-end router onto an off-box computation engine.
To perform Constraint-based Path Computation (CSPF). you need to configure external components outside of the router. The goal of the PCE architecture is to provide special computation components for computing CSPF, especially for more complex use-cases such as Inter-domain path establishment or wholly diverse paths. The PCE architecture also provides a foundation for more general use-cases such as the coupling of powerful computation services with less sophisticated or resource constrained head-end or ingress Label Edge Routers (LERs) that are becoming more and more prevalent in modern networks.
Use Case Inter-domain Path
The cPCE architecture provides components for computing CSPF in the use cases such as inter-domain path establishment or wholly diverse paths.
Use Case Compute Offload
cPCE is useful for computing and delegating traffic-engineered label-switched paths (LSPs) in an RSVP-Traffic Engineering (RSVP-TE) network development.
R0a, R0b, and R0c are ingress routers that are offloading path computation to cPCE. cPCE1a is acting as primary PCE and cPCE1b is secondary PCE. cPCE2a primary is catering to R4 using PCEP messages and cPCE2b is secondary.
Use case eODN
This use case describes cPCE distributed enhanced On-Demand Nexthop (eODN) use case in a network deployment where Segment Routing traffic engineering (TE) is used as the path-control technology. eODN is a TE use case where interdomain TE tunnels or policies are dynamically computed and placed when a BGP VPN route arrives on an ingress node with a protocol nexthop for a destination from remote domain.
Domain specific cPCE enables inter-domain on-demand SR policy creation. Each domain has one or more redundant cPCE responsible for inter-domain computation services.
Overview
cPCE combines multiple Junos components to form a PCE. These components are shown in Figure 4 Each container instance is individually manageable through Junos CLI.
The cPCE comprises of the following services as shown in Figure 5:
- Path Computation Element (PCE) Communication Protocol (PCEP) session management and maintenance
- Topology acquisition
- Path computation
cPCE offers the flexibility to deploy a PCE in different ways; on-box, or off-box, or as a third party application on Junos OS Evolved. Furthermore, you can deploy cPCE in a scale-out fashion to cater to the specific scalability, redundancy, or performance needs of a given deployment
The cPCE solution consists of two containerized components.
- cPCEPAdaptor
- cPCE (cRPD)
PCEP describes the protocol for PCE and Path Computation Client (PCC) to communicate with each other. PCEP provides mechanisms for PCEs to perform path computations in response to PCC requests.
PCEP extends the PCE communication protocol for stateful PCEs by specifying a set of extensions to PCEP to enable stateful control of LSPs within and across PCEP sessions. It includes mechanisms to effect LSP state synchronization between PCCs and PCEs, delegation of control over LSPs to PCEs, and PCE control of timing and sequence of path computations within and across PCEP sessions.
cPCEPAdaptor container instance handles the PCEP messages and maintains the LSP state. cPCE (cRPD) instance provides the actual path computation service. The cPCE instance learns topology information from BGP-LS connections.
The cPCEPAdaptor processes the PCEP reports from the ingress PCC device and triggers path-computation requests and sends them to the cPCE. The cPCE receives the set of constraints for the LSP and delivers computation results to the cPCEPAdaptor.
Benefit of cPCE
- Scale out compute services
Licensing
You need a license to activate cPCE software features. To understand more about cPCE licenses, see Flex Licenses for cRPD, Flex Software License Model, and Managing cRPD Licenses.