A shared mesh protection scheme defines an associated protection path when a
working
connection is established. During the protection path definition, the corresponding
protection path information is sent down to a switch card of network elements making
up the protection path. Upon detection of the failure, the network elements using
an overhead byte message will inform the routing source network element of the
connection of the failure in the working path. The overhead bytes used are interrupt
driven bytes located in the line and path overhead of network traffic. The routing
source node of the connection will then send the corresponding overhead byte messages
down the protection path to provide for protection path establishment according
to the preloaded data located at the switch card. It should be noted that each
connection can have a source and termination element which relates to the source
from where the corresponding connection was set-up rather than the direction of
the payload transmission. Therefore, once the failure has occurred the source elements
will send messages using overhead bytes to the corresponding network elements along
the protection path. Accordingly, routing tables located at the switch card of
the network elements, set-up when the working path connections were initially established,
determine this dynamically allocated protection path environment.
