Nokia 7705 - Page 309

MPLS Guide PCEP
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The PCE module uses PCEP to communicate with its PCE Clients (PCCs). It also
uses PCEP to communicate with other PCEs to coordinate inter-domain path
computation. Each router acting as a PCC initiates a PCEP session to the PCE in its
domain.
When the user enables PCE control for one or more segment routing (SR) or
RSVP-TE LSPs, the PCE owns the path updating and periodic reoptimization of the
LSPs. In this case, the PCE acts in an active stateful role. The PCE can also act in
a passive stateful role for other LSPs on the router by discovering the LSPs and
taking into account their resource consumption when computing the path for the
LSPs it has control ownership of.
The following is a high-level description of the PCE and PCC capabilities:
• base PCEP implementation, as per RFC 5440
• active and passive stateful PCE LSP update, as per draft-ietf-pce-stateful-pce
• delegation of LSP control to the PCE
• synchronization of the LSP database with network elements for PCE-controlled
LSPs and network element-controlled LSPs
• support for PCC-initiated LSPs, as per draft-ietf-pce-stateful-pce
• support for LSP path diversity across different LERs using extensions to the
PCE path profile, as per draft-alvarez-pce-path-profiles
• support for LSP path bidirectionality constraints using extensions to the PCE
path profile, as per draft-alvarez-pce-path-profiles