Bidirectional path with asymmetric path properties

italobusi commented 4 years ago

The module misses a mechanism to include a metric's accumulative-value per direction, e.g. we could have a bidirectional WDM LSP with 2 different SNR values, one for downstream and one for downstream; a possible solution could be to add an optional "upstream" branch carrying relevant properties.

See: https://github.com/rvilalta/ietf-te-path-computation/issues/65

italobusi commented 4 years ago

I think we should consider the following cases:

               - symmetric constraints ----- symmetric properties
             /                         \
            /                           \
bidir path -                             \
            \                             \
             \- asymmetric constraints ----- asymmetric properties

tsaad-dev commented 4 years ago

The model has provision for reverse-path-properties for bidirectional. The reverse path properties are displayed under the reverse-path.

The reverse-path is configured for non-corouted case The reverse-path is not configured for co-routed. The properties for computed path can always be displayed under the reverse path

The forward path has constraints and properties If the reverse path is configured, then the bidirectional tunnel "can" be asymmetric and non-co-routed. The reverse path properties can be specified differently from the forward path

tsaad-dev commented 4 years ago

note: for asymmetric BW can be specified different in forward/reverse

italobusi commented 4 years ago

See also discussions in open issues #25 and #83

tsaad-dev commented 4 years ago

Co-routed:

bidirectional is set ON
To have asymmetric constraints, specify constraints under reverse path
To have symmetric, only specify constraints in the forward path

tsaad-dev commented 4 years ago

Open issue for secondary. AI(Italo): to produce example and highlight issue

italobusi commented 4 years ago

Some slides describing my doubts: tunnel-paths-01.pptx

Main questions:

How to know which secondary-reverse path is co-routed with which secondary-path: see slide 4
When constraints are configured only for the forward path, how to distinguish between the configuration of a bidirectional tunnel with symmetric constraints requesting symmetric properties or asymmetric properties: see slide 5

italobusi commented 3 years ago

Slides updated based on the 2021-02-12 discussion: tunnel-paths-03.pptx

Some slides describing my doubts: tunnel-paths-01.pptx

Main questions:

How to know which secondary-reverse path is co-routed with which secondary-path: see slide 4

Use the order in the Candidate-Secondary-list and in the Rev-Candidate-Secondary-list: the nth element of the Rev-Candidate-Secondary-list is co-routed with the nth element in the Candidate-Secondary-list (see updated slide 4)

When constraints are configured only for the forward path, how to distinguish between the configuration of a bidirectional tunnel with symmetric constraints requesting symmetric properties or asymmetric properties: see slide 5

When requesting asymmetric properties, the reverse path are configured:

An empty explicit-route-object is configured to request the reverse path to be co-routed with the primary path.
Empty path constraints are used to configure symmetric path constraints (by default, path constraints which are not specified for the reverse path are assumed to be the same as the path constraints specified for the primary path)

italobusi commented 2 years ago

JSON code for the examples in tunnel-paths-03.pptx: tunnel-paths-03-00.zip