Figure 39: Example PCE for MPLS RSVP-TE
This way, the stateful PCE provides a cooperative operation of distributed functionality
used to address specific challenges of a shortest interdomain constrained path
computation. It eliminates congestion scenarios in which traffic streams are inefficiently
mapped onto available resources, causing overutilization of some subsets of network
resources, while other resources remain underutilized.
LSP Behavior with External Computing
•
LSP Types on page 701
•
LSP Control Mode on page 702
LSP Types
In a client-side PCE implementation, there are three types of TE LSPs:
•
CLI-controlled LSPs—The LSPs that do not have the lsp-external-controller pccd
statement configured are called CLI-controlled LSPs. Although these LSPs are under
local control, the PCC updates the connected PCEs with information about the
CLI-controlled LSPs during the initial LSP synchronization process. After the initial LSP
synchronization, the PCC informs the PCE of any new and deleted LSPs as well.
•
PCE-controlled LSPs—The LSPs that have the lsp-external-controller pccd statement
configured are called PCE-controlled LSPs. The PCC delegates the PCC-initiated LSPs
to the main PCE for external path computation.
The PCC informs the PCE about the configured parameters of a PCE-controlled LSP,
such as bandwidth, ERO, and priorities. It also informs the PCE about the actual values
used for these parameters to set up the LSP including the RRO, when available.
The PCC sends such LSP status reports to the PCE only when a reconfiguration has
occurred or when there is a change in the ERO, RRO, or status of the PCE-controlled
LSPs under external control.
701Copyright © 2017, Juniper Networks, Inc.
Chapter 23: Configuring Path Computation Element Protocol (PCEP)
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