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frr/doc/developer/path-internals.rst

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pathd: New SR-TE policy management daemon This new daemon manages Segment-Routing Traffic-Engineering (SR-TE) Policies and installs them into zebra. It provides the usual yang support and vtysh commands to define or change SR-TE Policies. In a nutshell SR-TE Policies provide the possibility to steer traffic through a (possibly dynamic) list of Segment Routing segments to the endpoint of the policy. This list of segments is part of a Candidate Path which again belongs to the SR-TE Policy. SR-TE Policies are uniquely identified by their color and endpoint. The color can be used to e.g. match BGP communities on incoming traffic. There can be multiple Candidate Paths for a single policy, the active Candidate Path is chosen according to certain conditions of which the most important is its preference. Candidate Paths can be explicit (fixed list of segments) or dynamic (list of segment comes from e.g. PCEP, see below). Configuration example: segment-routing traffic-eng segment-list SL index 10 mpls label 1111 index 20 mpls label 2222 ! policy color 4 endpoint 10.10.10.4 name POL4 binding-sid 104 candidate-path preference 100 name exp explicit segment-list SL candidate-path preference 200 name dyn dynamic ! ! ! There is an important connection between dynamic Candidate Paths and the overall topic of Path Computation. Later on for pathd a dynamic module will be introduced that is capable of communicating via the PCEP protocol with a PCE (Path Computation Element) which again is capable of calculating paths according to its local TED (Traffic Engineering Database). This dynamic module will be able to inject the mentioned dynamic Candidate Paths into pathd based on calculated paths from a PCE. https://tools.ietf.org/html/draft-ietf-spring-segment-routing-policy-06 Co-authored-by: Sebastien Merle <sebastien@netdef.org> Co-authored-by: Renato Westphal <renato@opensourcerouting.org> Co-authored-by: GalaxyGorilla <sascha@netdef.org> Co-authored-by: Emanuele Di Pascale <emanuele@voltanet.io> Signed-off-by: Sebastien Merle <sebastien@netdef.org>
2020-07-31 18:04:20 +02:00
.. _path_internals:
*********
Internals
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.. toctree::
:maxdepth: 2
path-internals-daemon
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