Motorola PowerQUICC II MPC8280 Series Reference Manual page 1058

ATM Memory Structure
Table 31-14. GMODE Field Descriptions (continued)
Bits Name
1
8 REM Receive emergency mode
0 Enable REM operation. When the receive FIFO is full, the ATM transmitter stops sending data
cells until the receiver emergency state is cleared (FIFO not full). The transmitter pace is
maintained, although a small CDV may be introduced. This mode enables the receiver to receive
bursts of cells above the steady state performance.
1 Disable REM operation. Note that to check system performance the user may want to set this bit.
9–10 — Reserved, should be cleared.
10 IMA_E MPC8264 and MPC8266
N 0 Default. FCC Enabled in normal ATM mode
1 FCC enabled in IMA mode
Note that individual PHYs of those IMA-mode enabled FCCs may still be set for non-IMA
functionality via the IMAPHY register in the IMA root table.
11 UEAD User-defined cells extended address mode. See Section 31.7.1, "UDC Extended Address Mode
(UEAD)."
0 Disable UEAD mode.
1 Enable UEAD mode.
12 CUAB Check unallocated bits
0 Do not check unallocated bits during address compression.
1 Check unallocated bits during address compression.
13 EVPT External address compression VP table
0 VP table resides in dual-port RAM.
1 VP table reside in external memory.
14 — Reserved, should be cleared.
15 ALM Address look-up mechanism. See Section 31.4, "VCI/VPI Address Lookup Mechanism."
0 External CAM lookup.
1 Address compression.
1
MPC8264 and MPC8266 only: GMODE[REM] must be set to disable receive emergency mode. If receive emergency
mode were enabled, it would result in IMA transmit protocol violations in cases of system overload, potentially
avoiding protocol errors in the IMA receiver at the expense of generating IMA transmit protocol violations to the far
end. Rather than causing erratic transmit operation, it is better to set GMODE[REM] and deal with the IMA receive
protocol violations locally. Note further that the system should be designed such that overload problems never occur
in the field; any errors due to overload should be eliminated during system design and debug.
31.10.2 Connection Tables (RCT, TCT, and TCTE)
The receive and transmit connection tables, RCT and TCT, store host-initialized connection
parameters after connection set-up. These include AAL type, connection traffic parameters,
BD parameters and temporary parameters used during segmentation and reassembly
(SAR). The transmit connection table extension (TCTE) supports special connections that
use ABR, VBR or UBR+ services. Each connection table entry resides in a 32-byte space.
Table 31-15 lists sizes for RCT, TCT, and TCTE.
31-44
Freescale Semiconductor, Inc.
only: Enable the associated FCC in IMA mode.
MPC8280 PowerQUICC II Family Reference Manual
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