Segment protection

Segment protection is a type of backup technique that can be used in most networks. It can be implemented as a dedicated backup or as a shared backup protection. Overlapping segments and non-overlapping segments are allowed; each providing different advantages.

In "Working path" animation on the right it can be seen that for a chosen route the primary path becomes the working path. This example illustrates that the source (node A) is routed to B,then C,D,E, and lastly the destination (node F). We can see that segment protection has been implemented. Segment ${\displaystyle Alpha}$ consists of nodes A, B, C, and D while segment ${\displaystyle Beta}$ consists of nodes C, D, E, and F. Lets assume that link B-C failed. Nodes B and C know that the link between them is down so they signal to their neighboring nodes that a link is down and to move to a backup path. Node A sends its traffic over to node D directly. Node D then sends the traffic over its route to E then finally destination F.

Note: in this case the segment protection path for segment ${\displaystyle Alpha}$ does not contain any intermediate nodes; this is usually not the case, but the example would follow respectively.

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