In MSP networking, when optical fiber is connected between sites, the east optical board of the site is connected to the west optical board of the downstream site, and these sites are connected in…

In MSP networking, when optical fiber is connected between sites, the east optical board of the site is connected to the west optical board of the downstream site, and these sites are connected in sequence to form a ring. In this case, the direction from the east optical board of the site to the west optical board of the downstream site is the main ring direction, and the direction of the ring is the service direction.