OptiX OSN 7500 
Technical Manual - System Description  6 Data Features 
Huawei Technologies Proprietary 
6-19 
Node 1
Node 2
Node 5
Node 6
Dual-ring
2.5 Gbit/s RPR
Node 4
Node 3
X
Fiber cut
Traffic flow
after switching
Traffic flow before
switching
 
Figure 6-17 Steering protection 
3.  Spanning Tree and LCAS 
For details about spanning tree and LCAS, refer to “6.1  Ethernet”. 
6.3  ATM Features 
This section describes the ATM features of the OptiX OSN 7500 in terms of 
functionality, application, and protection. 
6.3.1  Functions 
The OptiX OSN 7500 provides four different ATM processing boards: ADL4, ADQ1, 
IDL4 and IDQ1. The IDL4 and the IDQ1 support inverse multiplexing for ATM (IMA). 
An ADL4/IDL4 board can access and process one STM-4 ATM service and an 
ADQ1/IDQ1 board can access and process four STM-1 ATM services. When working 
with the PL3/PD3 board, the ADL4 board or ADQ1 board can access and process E3 
ATM services. The functions of the four boards are listed in Table 6-4. 
Table 6-4 Functions of the four ATM boards 
                Board 
Function  
ADL4/IDL4  ADQ1/IDQ1 
Front panel interface  1 x STM-4  4 x STM-1 
Optical interface index  S-4.1, L-4.1  I-1, S-1.1, L-1.1 
Optical interface type  Hot swappable LC (SFP)  Hot swappable LC (SFP)