Path Computation Element
charter-ietf-pce-07-01

The PCE Working Group is chartered to specify the required protocols
so as 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. Further, the PCE WG also
handles protocol extensions for 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) LSR, but on some other path computation entity
that may not be physically located on each head-end LSR. 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.

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

• Definition 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.

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

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

Milestones

• July 2023 Submit PCEP YANG Model as a Proposed Standard
• July 2023 Submit PCEP SRv6 extension as a Proposed Standard
• July 2023 Submit PCEP Native-IP extensions as a Proposed Standard
• Dec 2023 Submit PCEP extensions for SR Policy and Multipath
• July 2024 Submit Enhancements to Stateful PCE
• Evaluate WG progress, recharter or close