| 摘要 |
Protection switching between primary and secondary paths in a packet-based network involves table entries that are pre-programmed with a primary path, a secondary path, and a value that identifies the primary path, referred to as a primary path identifier (PPI). When table entries are accessed to make forwarding decisions, the PPI is compared to a field that identifies that a particular path is down, referred to as a down path identifier (DPI). If the two fields match, (i.e., PPI=DPI), then the secondary path is selected instead of the primary path as the path on which the traffic should be forwarded.
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