cx28224 Mindspeed Technologies, cx28224 Datasheet - Page 22

• Manufacturer Part Number: cx28224
• Description: Cx28224/5/9 Inverse Multiplexing For The Atm Ima Family
• Manufacturer: Mindspeed Technologies

Introduction to IMA
1.1.3
1.1.4
1-8
Link State Machine
Transmit Clocks
Management of the individual links is performed by two state machines: the Transmit
Link State Machine and the Receive Link State Machine. Four possible states are
available for each link as shown in
Table 1-3. Link States
The Link State Machines are responsible for handling the transition from one state to
another. All functions of the LSM's are performed internally by the CX2822x. Further
details are covered in
The IMA standard provides two options regarding the transmit clocks. The default
mode, and most common IMA application, is Common Transmit Clock (CTC) mode,
where all links in the IMA group are generated from the same source. Thus they are in
phase and have the same rate of SICP insertion (1/2049) as the designated TRL link.
The Independent Transmit Clock (ITC) mode is available as an optional feature of the
IMA protocol (of course, it is fully supported by the CX2822x family). In this mode,
each link runs off of an independent clock at the nominal line rate. To support these
asynchronous links within an IMA group, the rate of SICP insertion is allowed to vary
on the non-TRL links.
The IMA group frame rate for each IMA group must be re-created at the receive end.
This regeneration is necessary to implement the IMA Data Cell Clock and smoothing
buffer functionality of the IMA protocol. One method for generating the Receive IMA
group frame rate is to use the line or payload clock recovered from the receive TRL
physical port interface. This clock is a frequency locked reference of the far-end
Transmit IMA group frame rate. Equivalently, the rate of cell transfers (i.e., payload
bandwidth) from the TRL link can be used as the reference for generating the Receive
IMA group frame rate. Both methods are available for use by the CX2822x device,
depending on the application and configuration.
Not in Group
Unusable
Usable
Active
State
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Chapter 3
this link has not been added to an IMA group
the link is in a group but cannot be used due to line fault etc.
assigned to a group and ready but is waiting for the other end
fully configured and carrying traffic
and in the ATM standard on IMA.
Table
1-3.
™
Description
CX28224/5/9 Data Sheet
28229-DSH-001-D