Associated Bidirectional Non Co-Routed And Co-Routed Lsps - Cisco ASR 900 Series Manual
Mpls basic configuration guide, cisco ios xe everest 16.5.1
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- Release notes (310 pages) ,
- Configuration manual (172 pages) ,
- Configuration manual (19 pages)
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Associated Bidirectional Non Co-routed and Co-routed LSPs
Associated Bidirectional Non Co-routed and Co-routed LSPs
This section provides an overview of associated bidirectional non co-routed and co-routed LSPs. Establishment
of MPLS TE-LSP involves computation of a path between a head-end node to a tail-end node, signaling along
the path, and modification of intermediate nodes along the path. The signaling process ensures bandwidth
reservation (if signaled bandwidth is lesser than 0 and programming of forwarding entries).
Path computation is performed by the head-end nodes of both the participating LSPs using Constrained Shortest
Path First (CSPF). CSPF is the 'shortest path (measured in terms of cost) that satisfies all relevant LSP TE
constraints or attributes, such as required bandwidth, priority and so on.
Associated Bidirectional Non Co-routed LSPs: A non co-routed bidirectional TE LSP follows two different
paths, that is, the forward direction LSP path is different than the reverse direction LSP path. Here is an
illustration.
In the above topology:
• The outer paths (in green) are working LSP pairs.
• The inner paths (in red) are protecting LSP pairs.
• Router 1 sets up working LSP to Router 3 and protecting LSP to Router 3 independently.
• Router 3 sets up working LSP to Router 1 and protecting LSP to Router 1 independently.
Non co-routed bidirectional TE LSP is available by default, and no configuration is required.
In case of non co-routed LSPs, the head-end nodes relax the constraint on having identical forward and
Note
reverse paths. Hence, depending on network state you can have identical forward and reverse paths, though
the bidirectional LSP is co-routed.
MPLS Basic Configuration Guide, Cisco IOS XE Everest 16.5.1 (Cisco ASR 900 Series)
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Flex LSP Overview
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