OptiX OSN 7500
Technical Manual - System Description
6 Data Features
Huawei Technologies Proprietary
6-22
Note: The OptiX OSN products do not support the number 8 traffic type, which is for ABR services.
2.
Application of Band Exclusive ATM Services
When the bandwidth is not shared, ATM services at the source and sink NEs are only
processed at the ATM layer through the ATM service process board. On intermediate
NEs, only SDH timeslot pass-through is performed, without ATM layer processing. In
this case, each ATM service has the whole VC3/VC4 channel to itself. The ATM
services are converged at the central node and then multiplexed to an STM-1 or
STM-4 optical port for output. As shown in the Figure 6-18, the 34 Mbit/s ATM services
of NE1 and NE3 each occupy a VC3 bandwidth. The 155 Mbit/s ATM service of NE2
occupies a VC4 bandwidth alone. SDH timeslot pass-through is only performed at
NE3. After they reach the central site NE4, they are converged through the ATM board
and output through the 622 Mbit/s optical interface.
2.5 Gbit/s SDH
Ring
NE 2
NE 4
NE 1
NE 3
34M ATM
Traffic
34M ATM
Traffic
155M ATM
Traffic
622M ATM
Traffic
Service
Convergence
DSLAM
DSLAM
Router
DSLAM
Figure 6-18
Application of Band exclusive ATM Services
3.
Application of Band-Shared ATM Services
In shared rings VR-Ring and VC-Ring, the ATM services share the same bandwidth
and are multiplexed statistically. The ATM services on each NE share the same VC
(VC3, VC4, or VC-Xv) and are all processed on ATM layer. As shown in the Figure
6-19, NE1 accesses E3 ATM traffic through the tributary board and sends it to the ATM
board for ATM switching and protection (1+1/1:1) configuration. Then the traffic is
encapsulated into VC4-Xv and sent to the line through the cross-connect board. NE2
