MT90883 Zarlink Semiconductor, MT90883 Datasheet - Page 36

• Manufacturer Part Number: MT90883
• Description: (MT90880 - MT90883) TDM to Packet Processors
• Manufacturer: Zarlink Semiconductor

5.4.3
The MT9088x family uses a two-byte field within the packet header to convey which context the packet belongs
to. The format of the field is as follows:
Field definitions
5.5
5.5.1
The establishment of a context to carry TDM data across a packet network is a negotiated process. The call
parameters (e.g. the context ID label, number of channels to be included, number of frames) must be agreed
between the host CPU's at either end of the packet network. Similarly, subsequent changes to a context must also
Context ID A unique number identifying the context to the receiving device. The Context ID is assigned by the
CS
Ver
Context Negotiation and Establishment
Context Descriptor Protocol
Overview
receiving device during context establishment.
The MT9088x only supports values in the range 0-127, and hence bits 7-11 must be set to zero.
Context Switch Bit. This bit toggles when there is a change to the context, e.g., addition or
deletion of new timeslots from the packet. The toggle action ensures that the change to the
context is still signalled even if the first packet indicating the change is lost.
Protocol version number.
For the MT9088x family, the version number is always zero.
Data for TDM Frame 1
Data for TDM Frame 2
Data for TDM Frame n
Fixed Header
Figure 18 - Packet Structure for MT9088x Family
15
Ver.
Figure 19 - Context Descriptor Field
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C
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Zarlink Semiconductor Inc.
MT90880/1/2/3
Static Padding (if required)
Upper Layers (optional)
Context Descriptor
Ethernet Header
Ethernet FCS
Channel 1
Channel 2
Channel 1
Channel 2
Channel 1
Channel 2
8 7
Channel x
Channel x
Channel x
Context ID
36
0
Ethernet Payload
46 to 1500 bytes
Data Sheet