Pcep Extensions In Support Of Sr-Te Lsps - Nokia 7705 SAR-W Series Manual

PCEP

4.4.3 PCEP Extensions in Support of SR-TE LSPs

In order for the PCE and PCC to manage the path of an SR-TE LSP, they both
implement the following extensions to PCEP in support of segment routing.
318
- The value of the metric or bandwidth in the duplicate object contains the
original constraint value, while the first object contains the operational
value. This is applicable to hop metrics in the metric object and bandwidth
object only. The 7705 SAR PCC does not support putting a bound value on
the IGP or TE metric in the path computation.
- The path computation on the PCE uses the first set of objects when
updating a path if the PCRpt message contains a single set. If the PCRpt
message contains a duplicate set, PCE path computation must use the
constraints in the duplicate set.
- For interoperability, implementations compliant with PCEP standards
should be able to accept the first metric object and ignore the second object
without additional error handling. Because there are also bandwidth and
LSPA objects, the [no] report-path-constraints command is provided in
the PCC on a per-PCEP session basis to disable the inclusion of the
duplicate objects. Duplicate objects are included by default.
• The PCC and PCE support a Segment Routing capability TLV in the OPEN
object to indicate support of segment routing tunnels by the PCE and the PCC
during PCEP session initialization. This TLV is referred to as the SR-PCE-
CAPABILITY TLV.
• The PCC and PCE support all PCEP capability TLVs defined in this chapter and
will always advertise them. If the OPEN object received from a PCEP speaker
does not contain one or more of the capabilities, the PCE or the PCC will not use
them during that specific PCEP session.
• The PCC and PCE support a new Path Setup Type TLV for SR-TE LSPs to be
included in the Stateful PCE Request Parameters (SRP) object during path
report (PCRpt) messages by the PCC.
A Path Setup Type TLV with a value of 1 identifies an SR-TE LSP.
• The PCC and PCE support a new Segment Routing ERO and RRO with
sub-objects, referred to as SR-ERO and SR-RRO sub-objects, which encode
the SID information in PCRpt messages.
Use subject to Terms available at: www.nokia.com
© 2022 Nokia.
MPLS Guide
3HE 18686 AAAB TQZZA