An Introduction to the Ericsson Transport Network Architecture ...

AXD 4/1, a Digital Cross-Connect
System
Jan A Bergkvist, Giovanni Evangelisti and Jan Hopfinger
AXD 4/1 is one of the new cross-connect products in the ETNA - Ericsson Transport
Network Architecture - concept. The system is designed to meet the different needs
of an evolving network that will include both SDH and PDH equipment.
The authors describe the system architecture and the present system implementation.
Fast service provisioning, supervision providing
guaranteed high-quality leased
lines with capacities ranging from 2 Mbit/s
up to VC-4 (155 Mbit/s), fast network configuration
and better network administration
are some of the benefits of an
AXD 4/1. 3
digital communication systems
telecommunication networks
telecommunication network management
The AXD 4/1 is a digital Cross-Connect
system which terminates digital signals
and cross-connects these signals or their
tributary parts. The extensive switching
and supervision facilities of the AXD 4/1
system makes it suitable for a wide range
of applications involving network provision
and network protection.
The AXD 4/1 is a vital component in the
ETNA network solution, offering fast service
provisioning and high availability.
The AXD is a switch that differs from an ordinary
telephony switch in three ways:
- It is controlled by commands from an operating
system or an operator and not by
embedded control information in the
transmitted signals
- The holding times for a connection are
days or weeks, as compared with minutes
for a telephony switch
- The bandwidth of the switched signals is
in the range 1.5-155 Mbit/s, compared
with 64 kbit/s.
Functions
The AXD 4/1 system replaces the manual
distribution frames and multiplexers used
in the present network.
The AXD 4/1 cross-connects signals at all
VC levels (VC-12 to VC-4) according to the
SDH standard, corresponding to
2-155 Mbit/s. Both PDH and SDH signals
can be terminated and cross-connected simultaneously
in the same system, Table 1.
The specification of the system's internal
interfaces allows all sixty-four 2 Mbit/s and
all four 34 Mbit/s signals in a 140 Mbit/s
signal to be used. This means that the introduction
of SDH in the PDH network will
entail no network restrictions.
In addition to the cross-connect functions,
the AXD 4/1 adds extensive supervision
functionality to the network. All terminated
signals are continuously supervised for
performance and fault. Combined with a
central network management system,
Fig. 1
Operators working with the AXD system
ERICSSON REVIEW No. 3, 1992