Marconi OMS 1200
Technical Product Description
221 02-ZAP 701 25/1 Rev C 2006-08-04
© Ericsson AB 2006
03PHB00004AAV-CUA
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7.12.1 Ring
Switch
There is only a single physical section around the Ring. Normal traffic connections are
set up on the allocated Worker channels (for example. channels #1–8). Protection
channels, which are normally idle (i.e. Protection channels #9–16), provide a shared
resource for channel protection switching.
Transmission Failure
When there is a complete failure of both Worker and Protection sections on the Span
between Nodes B and C, then a full Ring switch is required to restore the transport
circuit X traffic. Node B senses the failure and Bridges Working channels East-bound
onto Protection channels West-bound, away from the failure. Nodes F, E and D
provide pass-through connections for the protected traffic to complete a path to Node
C. In response to the Bridge at Node B, Node C Switches the protected traffic from
East back onto Worker channels East-bound. Node D now receives the working traffic
from West, as if no failure had occurred.
In the reverse direction of transmission, with Node C also detecting failure, it would
Bridge Working channels West-bound onto Protection channels East-bound, away
from the failure and Node B would Switch the protected traffic from West back onto
Worker channels West-bound. Node A then, is not aware of failure either.
Note:
Transport circuit Y is unaffected by the protection switching. Likewise, circuit
connections between, Node B and Node A, or B and F via A, are not
affected by the protection switching.
Note:
As both Worker and Protection sections are transported on the same
physical medium, there are no Span Switch options in 2–Fibre Rings.
