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Path Computation Element

Document Charter Path Computation Element WG (pce)
Title Path Computation Element
Last updated 2023-12-19
State Approved
WG State Active
IESG Responsible AD John Scudder
Charter edit AD John Scudder
Send notices to (None)


The PCE Working Group is chartered to specify the required protocols
to enable a Path Computation Element (PCE)-based architecture for the
computation of paths for MPLS and GMPLS Point to Point and Point to
Multi-point traffic-engineered LSPs, as well as new path setup types
of Segment Routing (SR), BIER, and Detnet.

In this architecture path computation does not necessarily occur on
the head-end (ingress) node, but on some other path computation
entity that may not be physically located on each head-end node. The
TEAS Working Group is responsible for defining and extending
architectures for Traffic Engineering (TE) and it is expected that the
PCE and TEAS WGs will work closely together on elements of TE
architectures that utilize PCE.

The PCE WG works on the application of this model within a single
domain or within a group of domains (where a domain is a layer, IGP
area, or Autonomous System with limited visibility from the head-end
LSR). At this time, applying this model to large groups of domains
such as the Internet is not thought to be possible, and the PCE WG
will not spend energy on that topic.

The WG specifies the PCE communication Protocol (PCEP) and needed
extensions for communication between Path Computation Clients (PCCs)
and PCEs, and between cooperating PCEs. Security mechanisms such as
authentication and confidentiality are included.

The WG works on the mechanisms for inter-domain as well as multi-layer
path computation and PCEP extensions for communication between several
domains or network layers.

The WG defines the required PCEP extensions for Wavelength Switched
Optical Networks (WSON) and Flexible Grid while keeping consistency
with the GMPLS protocols specified in the CCAMP and TEAS WGs.

Work Items:

  • PCEP extensions to support MPLS and GMPLS Traffic Engineered LSP
    path computation models involving PCEs. This includes the case of
    computing the paths of intra- and inter-domain TE LSPs. Such path
    computation includes the generation of primary, protection, and
    recovery paths, as well as computations for (local/global)
    reoptimization and load balancing. Both intra- and inter-domain
    applications are covered.

  • In cooperation with the TEAS Working Group, development of PCE-
    based architectures for Traffic Engineering including PCE as a
    Central Controller (PCECC) and Centralized Control Dynamic Routing
    (CCDR). The PCEP extensions are developed in the PCE Working Group.

  • In cooperation with protocol-specific Working Groups (e.g., MPLS,
    CCAMP), development of LSP signaling (RSVP-TE) extensions required
    to support PCE-based path computation models.

  • Specification of PCEP extensions for expressing path computation
    requests and responses in the various GMPLS-controlled networks,
    including WSON and Flexible Grid.

  • Specification of PCEP extensions for path computation in multi-layer
    and inter-domain networks.

  • Specification of the PCEP extensions used by a stateful PCE for
    recommending a new path for an existing or new LSP to the PCC/PCE.
    Further protocol extensions must cover the case where the receiving
    PCC/PCE chooses not to follow the recommendation. The PCEP
    extensions for state synchronization are also in scope.

  • Specification of the PCEP extensions for SR-MPLS and SRv6 paths as
    per the SR Policy architecture in cooperation with SPRING Working

  • Specification of the PCEP extensions for new path setup types (such
    as BIER and DETNET) in cooperation with the respective Working