zl50118gag2 Zarlink Semiconductor, zl50118gag2 Datasheet - Page 43

• Manufacturer Part Number: zl50118gag2
• Description: 32 Channel 1 T1/e1 Cesop Processor With Single Ethernet Interface
• Manufacturer: Zarlink Semiconductor

5.0
5.1
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, in unstructured mode, 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.
Leased Line Provision
Typical Applications
Customer
Premises
f
service
~
Figure 8 - Leased Line Services Over a Circuit Emulation Link
TDM
Provider Edge
Interworking
Function
TDM to
ZL50115/16/17/18/19/20
packet
Zarlink Semiconductor Inc.
Carrier Network
Network
Packet
43
Provider Edge
queue
Interworking
Function
f
service
~
TDM
Customer
Premises
Extract
Clock
f
service
Data Sheet