PCEP Protocol

Team

Overview

This project adds Path Computation Element Protocol (PCEP) as a southbound plugin in ONOS.

Proposed work

Add PCEP South Bound Interface (SBI) for MPLS TE tunnel management which will implement TunnelProvider API to support initiating, updating and releasing of PCE initiated tunnels using PCE communication protocol. The implementation will also support learning of existing active tunnels which are on the network.

Implement PCEP protocol handler, which acts as a server to listen on PCEP port 4189 to establish and manage session with PCCs. A channel handler will be created for each PCEP session to maintain the state machine and state of each PCC.

Implement PCEP message handler, which will encode and decode PCEP messages between ONOS PCEP SBI and PCC. Currently the messages supported are Open, KeepAlive, PCInitiate, PCUpd, PCRpt, PCLabelUpd, TE Report, PCLRResv, PCErr and Close.

Implementation supports state synchronization with PCC reporting reporting LSPs’ state to PCEP protocol handler running on ONOS immediately after session established. These report messages are notified to PCEP Tunnel Provider via message listener which in turn will inform the ONOS Core about the existing tunnels in the network. The Report message can also be the result of PCE initiated messages for creating, updating or releasing tunnels. In this case PCEP Tunnel Provider will invoke the respective API to notify ONOS Core about the result of create or update or release tunnels. All communication between PCEP provider and ONOS Core uses Provider Service interface.

SetupTunnel API

Arguments: Tunnel, Path

Return Value: None

Details: This API is responsible for setting up a tunnel on the device. It gets the tunnel parameters from the input parameters Tunnel and Path. The API implementation builds the PCInitiate protocol message from the input parameters. The ingress and egress are taken from src and dst members of Tunnel class. The ingress is considered as source for the tunnel and PCInitiate message is sent to ingress device for which a session is already established with the PCEP protocol handler. The explicit route object is built from the link parameter in the input Path class. The API implementation will take care of generating unique ID for sending the message to PCC and mapping the response from PCC. Finally the response is given to ONOS core using PCEP tunnel provider service.

UpdateTunnel API

Arguments: Tunnel, Path

Return Value: None

Details: This API is responsible for modifying an existing tunnel on the device. It gets the tunnel parameters from the input parameters Tunnel and Path. The API implementation builds the PCUpd protocol message from the input parameters. To send a PCUpd message the ingress device should have a tunnel which is already created and the PCE must be the owner of this tunnel. The ingress and egress for the tunnel are taken from src and dst of Tunnel class. The ingress is considered as source for the tunnel and PCUpd message is sent to ingress device for which a session is already established with the PCEP protocol handler. The explicit route object is built from link parameter in the Path class. The API implementation will take care of generating unique ID for sending the message to PCC and mapping the response from PCC. Finally the response is given to ONOS core using PCEP tunnel provider service.

ReleaseTunnel API

Arguments: Tunnel

Return Value: None

Details: This API is responsible for deleting an existing tunnel on the device. It gets the tunnel parameters from the input parameter Tunnel. The API implementation builds the PCInitiate protocol message from the input parameters. To send a PCInitiate message with delete flag set, the ingress device should have a tunnel which is already created and the PCE must be the owner of this tunnel. The tunnel id, ingress and egress for the tunnel are taken from tunnel id, src and dst of Tunnel class. The ingress is considered as source for the tunnel and PCInitiate message is sent to ingress device for which a session is already established with the PCEP protocol handler. The API implementation will take care of generating unique ID for sending the message to PCC and mapping the response from PCC. Finally the response is given to ONOS core using PCEP tunnel provider service.

Messages Supported

Open Message

Open message is used to establish a PCEP session between PCEP peers.  This carries various session characteristics like keep alive time, dead time and capability.

Supported TLVs

GMPLS-CAPABILITY TLV

STATEFUL-PCE-CAPABILITY TLV

PCECC CAPABILITY TLV

KeepAlive Message

    Keep alive message used to keep the session active and also in response to open messages while session establishment to acknowledge Open messages and session characteristics are acceptable.

    Supported TLVs

        Not Applicable

PCInitiate Message

    Setup Tunnel API will build the PCInitiate message to setup a tunnel at the PCC. The objects supported in PCInitiate message are

    SRP Object

        The SRP (Stateful PCE request parameters) object set the unique identifier for mapping   request/response between PCEP and PCC.

           Supported TLV’s

            Symbolic path name TLV

    LSP Object

        The LSP contains a set of fields used to specify the target LSP, the operation to be performed on the LSP and LSP delegation. It also contains a flag indicating to a PCE that the LSP state synchronization in progress.

         Supported TLV’s

            LSP identifiers TLV (IPV4)

            Symbolic path name TLV

            LSP Error code TLV

            RSVP Error Spec TLV      

    END POINTS Object

        The END POINTS object used to specify the source and destination IP addresses of the tunnel.

          Supported TLVs

           None.

    ERO Object

        Explicit route objects contain list of variable length SubObjects.

        Supported SubObjects

          IPv4 Prefix

          IPv6 Prefix

          Autonomous System number

          SR-ERO SubObject

          Path Key SubObject

    BANDWIDTH Object

        This object used to specify the requested bandwidth for a TE LSP.