363-206-295
Transmission and Synchronization Interfaces
5-6
Issue 1
December 1997
See Figure 5-3. For dual homed 0x1 ring applications, one function unit slot on the
OC-12 shelf must be empty. When the OC-12 shelf is provisioned for 0x1 (default)
operation, incoming Ring 1 (incoming to main B-1) always feeds (is locked to)
function unit ( )-1 and, therefore, main-1 of the OC-3 shelf. Similarly, incoming
Ring 2 (incoming to main B-2) always feeds (is locked to) Function
Unit ( )-2 and, therefore, main-2 of the OC-3 shelf.
Similarly, the TSI on the OC-12 shelf are locked so that Ring 1 output is always fed
from function unit ( )-2, and Ring 2 output is always fed from function unit ( )-1.
The Ring 1 input is always received on main B-1, and the Ring 2 input is always
received on main B-2.
When STS-1s are dropped to a 0x1 function unit, any fiber failure detected at
either the OC-3 shelf or OC-12 shelf will cause the OC-3 shelf to select all traffic
from the other ring.
