How does the XCE board of the OSN 3500 allocate bus timeslots to all slots in the extended subrack?
1. Two buses run from the main subrack to the extended subrack of the OSN 3500. Each bus works at a 622 Mbit/s rate.
2. For the OSN 3500 in a version earlier than V1R6, each slot actually uses a 1xVC4 bandwidth because the extended subrack supports only VC12 services (PQ1 and PQM). Hence, the XCE board allocates the 1xVC4 bus resource to each of slots 52, 53, 54, 55, 63, 64, 65, and 66 even if no board is inserted in a slot. In this case, the cross-connection matrix of the XCE board is invariable.
3. For the OSN 3500 in V1R6 or a later version, the extended subrack supports VC3 services, especially, the PD3 board, which needs the 2xVC4 bus resource. Hence, the bus resources of the extended subrack are allocated in the order of board insertion until the two buses (eight VC4s) are all allocated. The cross-connection matrix of the XCE board varies with the types of inserted boards and the order of board insertion.