4A0-205 Exam Dumps : Nokia Optical Networking Fundamentals

A degree-1 node is a node that only has one direction, and it is therefore a terminal node. This means that the node only has one input and one output port. It does not have any other ports to connect to other nodes or fibers. This is a common feature of some optical transport networks, such as ring networks, where a degree-1 node serves as the endpoint of the ring.

A trail is a transparent transport of a client signal. A trail is a physical link between two points in an optical network, allowing for the transport of a client signal from one point to the other. It is a low-order signal, such as a 10G Ethernet or a Fibre Channel signal, encapsulated into a high-order container, such as a 40G or 100G signal. This allows for the transport of the client signal over longer distances, increasing the power budget of the optical link.

There are two main mechanisms that can be put in place to increase network survivability: protection and restoration. Protection involves pre-allocating and reserving backup resources so that they are ready in case of a failure. Restoration involves allocating backup resources upon failure and using a 1+1 protection mechanism to recover each trail. This ensures that the network is able to re-route traffic in the event of a failure, increasing the overall survivability of the network.