PCEP Extensions for sid verification for SR-MPLS

describes the "SID verification" bit usage. SID verification is performed when the headend is explicitly requested to verify SID(s) by the controller via the signaling protocol used. Implementations MAY provide a local configuration option to enable verification on a global or per policy or per candidate path basis. specifies extensions to the Path Computation Element Communication Protocol (PCEP) that allow a stateful PCE to compute and initiate Traffic-Engineering (TE) paths, as well as a Path Computation Client (PCC) to request a path subject to certain constraints and optimization criteria in SR networks. This document defines a new flag for indicating the headend is explicitly requested to verify SID(s) by the PCE.

Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 when, and only when, they appear in all capitals, as shown here.

Section 4.3.1 in Path Computation Element Communication Protocol (PCEP) Extensions for Segment Routing describes a new ERO subobject referred to as the "SR-ERO subobject" to carry a SID and/or NAI information. A new flag is proposed in this doucument in the SR-ERO Subobject for indicating the pcc is explicitly requested to verify SID(s) by the PCE. V(1bit TBD): When the V-Flag is set then PCC MUST consider the "SID verification".

The format of the SR-RRO subobject is the same as that of the SR-ERO subobject, but without the L-Flag, per . The V flag has no meaning in the SR-RRO and is ignored on receipt at the PCE.

On receiving an SR-ERO with the V-flag is set, a PCC MUST verify SID(s) as described in Section 5.1 in . If a PCC "Verification fails" for a SID, it MUST report this error by including the LSP-ERROR-CODE TLV with LSP error-value "SID Verification fails" in the LSP object in the PCRpt message to the PCE.

We would like to thank Dhruv Dhody and John Scudder for their useful comments and suggestions.

This document defines a new bit value in the sub-registry "SR-ERO Flag Field" in the "Path Computation Element Protocol (PCEP) Numbers" registry.

The security considerations described in , , , and are applicable to this specification. No additional security measures are required.