Lsp Path Diversity And Bidirectionality Constraints - Nokia 7705 SAR-W Series Manual

PCEP
4.6 LSP Path Diversity and Bidirectionality
The PCE path profile defined in draft-alvarez-pce-path-profiles is used to request
path diversity or a disjoint for two or more LSPs originating on the same or different
PE routers. It is also used to request that paths of two unidirectional LSPs between
the same two routers use the same TE links. This is referred to as the bidirectionality
constraint.
Path profiles are defined by the user directly on the NRC-P Policy Manager with a
number of LSP path constraints, which are metrics with upper bounds specified, and
with an objective, which are metrics optimized with no bounds specified. The
NRC-P Policy Manager allows the following PCE constraints to be configured within
each PCE path profile:
The user can also specify which PCE objective to use to optimize the path of the LSP
in the PCE path profile, one of:
The CSPF algorithm will optimize the objective. If a constraint is provided for the
same metric, the CSPF algorithm ensures that the selected path achieves a lower or
equal value to the bound value specified in the constraint.
For hop-count metrics, if a constraint is sent in a metric object and is also specified
in a PCE profile referenced by the LSP, the constraint in the metric object is used.
For IGP and TE metrics, if an objective is sent in a metric object and is also specified
in a PCE profile referenced by the LSP, the objective in the path profile is used.
The constraints in the bandwidth object and the LSPA object, specifically the include
and exclude admin-group constraints and setup and hold priorities, are not
supported in the PCE profile.
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Constraints
• path diversity, node-disjoint, link-disjoint
• path bidirectionality, symmetric reverse route preferred, symmetric reverse
route required
• maximum path IGP metric (cost)
• maximum path TE metric
• maximum hop count
• IGP metric (cost)
• TE metric
• hops (span)
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