egress is a fiber break in the link between the two nodes.
a fiber break in the link between the two nodes?
egress
bidirectional line-switched ring (blsr) comes in two varieties: two-fiber blsr and four-fiber blsr. blsrs switch at the line layer. unlike upsr, blsr does not send redundant copies from ingress to egress. rather, the ring nodes adjacent to the failure reroute the traffic "the long way" around the ring on the protection fibers. blsrs trade cost and complexity for bandwidth efficiency, as well as the ability to support "extra traffic" that can be pre-empted when a protection switching event occurs. in four-fiber ring, either single node failures, or multiple line failures can be supported, since a failure or maintenance action on one line causes the protection fiber connecting two nodes to be used rather than looping it around the ring.
synchronous optical networking
bullet::::- fiber break locators are intended to be low-cost instruments specifically designed to determine the location of a catastrophic fiber event, e.g., fiber break, point of high reflectance, or high loss. the fiber break locator is an opto-electronic tape measure designed to measure only distance to catastrophic fiber events.
optical time-domain reflectometer