| 释义 |
Figure S-5 SDH and SONET standards specify two physical configuration options.A path-switched ring employs a dual counter-rotating ring, with both fibers active. One ring transmits in the clockwise direction and the other in the counter-clockwise direction.This approach offers zero downtime in the event of the failure of a fiber. A line-switched ring features one active and one inactive fiber. In the event of the catastrophic failure of a node or fiber, a line-switched ring offers sub-50 millisecond restoral times for rings up to 1,200 kilometers in route distance. Figure S-6 illustrates a hierarchy of local, metropolitan, and backbone rings operating at example OC-N rates. OC-3 OC-3 155 Mbps 155 Mbps |