cx28224 Mindspeed Technologies, cx28224 Datasheet - Page 19

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

CX28224/5/9 Data Sheet
1.1.2
Table 1-1. IMA Overhead Cell Definition (1 of 3)
28229-DSH-001-D
Octet
1-5
6
7
8
9
Frame Sequence Number
ATM Cell Header
ICP Cell Offset
IMA Label
Link ID
IMA Control Protocol Cells
Cell ID
Field
cells. This cell is called the SICP cell and is inserted immediately after the normal ICP
cell for that link and results in the frame being M+1 cells long. Information in the ICP
cell payload signals the insertion of these cells so that the receiver does not lose
framing and can identify and discard these cells. For further details consult the IMA
standard.
One link in each group is designated the Timing Reference Link (TRL). All timing
issues for the group are relative to this link.
The IMA Standard defines three types of IMA cells: IMA Control Protocol (ICP)
cells, Filler cells, and ATM layer cells. ICP cells are the IMA overhead cells that carry
the IMA control and status information between both ends of the link, assuring
synchronization and configuration. The purpose of filler cells is rate decoupling; they
are inserted into the IMA stream if no ATM layer cells are available.
ATM layer cells are the data “payload” carried by the IMA group. These are the
standard ATM cells being sent from the ATM layer.
Table 1-1
the IMA Overhead Stuff Cell.
NOTE:
OAM cell type: Octet 1 = 0000 0000
OAM type field:
Bit 7 Set to 1 for ICP cell
Bits 6–5 Unused and set to 0
Bits 4–0 Logical ID for physical link range (0... 31)
Cyclical counter: 0 to 255
Indicates position of ICP cell within the IMA frame of size M cells. Range: (0... M – 1)
describes the IMA Overhead Cell definition, and
Standard ATM 'idle' cells are never transmitted over an IMA link.
Octet 2 = 0000 0000
Octet 3 = 0000 0000
Octet 4 = 0000 1011
Octet 5 = 0110 0100 (valid HEC with Coset)
0000 0001—IMA Version 1.0
0000 0011—IMA Version 1.1
Mindspeed Technologies
Description
™
Table 1-2
lists format of
Introduction to IMA
1
-
5