User's Manual

14 4Motion System Manual
Chapter 1 - System Description
double-Euro slot is reserved for an optional redundant NPU (the shelf is HW-ready
for NPU redundancy). The remaining seven double-Euro slots are dedicated for
Access Unit (AU) modules, thereby enabling various network topologies and future
redundancy configurations. In addition, the shelf contains an Air Ventilation Unit
(AVU).
1.3.2 NPU
The Network Processing Unit is the controller of the Base Transceiver Station.
Serving as the central processing unit that manages the BTS components, the
NPU aggregates traffic to/from the AU modules, and transfers it to/from the IP
backbone through a dedicated Gigabit/Fast Ethernet interface. In addition, the
NPU can be operated in ASN-GW mode, in which case it also implements ASN-GW
functionality.
When operating in ASN-GW mode, the NPU implements the R3 reference point
toward the CSN, R4 reference point toward other ASN-GWs, and R6 reference
point toward AU/BSs. The R8 reference point traffic is transparently relayed
between AU/BSs (intra- or inter-BTS).
When operating in transparent mode, the NPU transparently relays R6 and R8
reference-point traffic between AU/BSs (intra- or inter-BTS).
The BreezeMAX shelf is hardware-ready for 1+1 NPU card redundancy.
The NPU main functions, when operating in transparent mode, are:
 Aggregate backbone Ethernet connectivity for user and control traffic
 Aggregate backbone Ethernet connectivity for management traffic (in-band or
out-of-band)
 Connection to a cascaded shelf (future feature)
 L2 switch forwarding capabilities
 Internal and external traffic VLAN encapsulation
 QoS marking
 Overall operation, control and shelf management, including AU diagnostics
and control, PSU monitoring, AVU management and redundancy support