MT90883 Zarlink Semiconductor, MT90883 Datasheet - Page 37

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

be agreed and synchronized between the two ends. The remote end is signalled to expect a modified context, and
its host sets up the new context information. This new setup is activated on receipt of the first packet containing the
new channel configuration.
This section describes the negotiation process that takes place at context establishment and modification. The
examples assume two MT9088x devices connected via a packet network. One device, the Packet Transmit End ,
receives bytes from the WAN, assembles them into packets and transmits them over the network. The second
device, the Packet Receive End , receives packets from the network, deconstructs them into bytes and transmits
them in their proper timeslots toward the destination. Each MT9088x device has its own host, denoted "PTX Host"
and "PRX Host".
The tables describe the process of context negotiation, rather than the protocol. The actual protocol can be chosen
to suit the overall application and customer requirements.
5.5.2
Table 15 describes the process for setting up a new context.
1
2
3
4
5
6
7
8
PTX Host sets up a new transmit context, assigning a
local context ID. This local context ID is used to
identify the context within the packet transmit device.
PTX Host signals Packet Receive host to expect a
new context, with details of the channels involved and
the destination channels.
PTX host completes context setup by placing the PRX
receive context ID into the packet header.
PTX host activates new context.
At the start of the next TDM frame, the MT9088x
commences formation of the first packet for the new
context. This packet is prepended with the new
packet header.
New Context Establishment
Packet Transmit End (PTX)
Table 15 - New Context Establishment
Zarlink Semiconductor Inc.
MT90880/1/2/3
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PRX Host sets up new receive context, assigning a
local context ID (this may not be the same as the
PTX's transmit context ID).
PRX host sends an acknowledgement back to the
PTX that the context is set up and ready to receive
packets.The PRX acknowledgement includes the
local receive context ID.
First packet received for the new context, identified
by the context ID label. Upon reception of packet
the MT9088x waits for a predetermined number of
TDM frames to allow for delay variation in the LAN,
then automatically activates new context. The
value of the context switch bit is recorded for
reference.
Packet Receive End (PRX)
Data Sheet