ZL50120 Zarlink, ZL50120 Datasheet - Page 42

• Manufacturer Part Number: ZL50120
• Description: 32 / 64 / 128 Channel CESoP Processors
• Manufacturer: Zarlink

ZL50115/16/17/18/19/20
Data Sheet
5.0
Typical Applications
5.1
Leased Line Provision
Circuit emulation is typically used to support the provision of leased line services to customers using legacy TDM
equipment. For example, Figure 8 shows a leased line TDM service being carried across a packet network. The
advantages are that a carrier can upgrade to a packet switched network, whilst still maintaining their existing TDM
business.
The ZL5011x is capable of handling circuit emulation of both structured T1, E1, and J2 links (e.g., for support of
fractional circuits) and unstructured (or clear channel) T1, E1, J2, T3 and E3 links. The device handles the
data-plane requirements of the provider edge inter-working function (with the exception of the physical interfaces
and line interface units). Control plane functions are forwarded to the host processor controlling the ZL5011x
device.
The ZL5011x provides a per-stream clock recovery function to reproduce the TDM service frequency at the egress
of the packet network. This is required otherwise the queue at the egress of the packet network will either fill up or
empty, depending on whether the regenerated clock is slower or faster than the original.
Carrier Network
Customer
Customer
Premises
Premises
Packet
queue
TDM
TDM
Network
TDM to
packet
f
service
~
Extract
~
Clock
f
f
service
service
Provider Edge
Provider Edge
Interworking
Interworking
Function
Function
Figure 8 - Leased Line Services Over a Circuit Emulation Link
42
Zarlink Semiconductor Inc.