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Table 9. DOS and OS/2 NDIS device driver parameters in PROTOCOL.INI (continued)
Parameter Explanation
MaxTxFrameSize (OS/2
only)
This parameter specifies the maximum frame size that can be transmitted on the LAN. The
parameter value serves as an upper limit. The actual maximum frame size might be smaller.
The maximum frame size supported by the NDIS device driver is the lesser of the following
values:
v The value of this MaxTxFrameSize parameter
v Total Receive Buffer Area (see the MinRcvBuffs parameter)
v The physical frame size capacity of the network (4500 bytes for 4-Mbps token rings and
18,200 bytes for 16-Mbps and 100-Mbps token rings)
Do not count the 4 bytes of FCS defined for a frame when setting this parameter value.
In some environments, performance can be increased by operating server and client at
larger frame sizes. Protocol frame size should be adjusted if this parameter is changed.
Note: Some token-ring switches support a maximum frame size of 4500 bytes.
Valid values: 14 to 18,000
The default is 4500.
MinRcvBuffs (OS/2 only) This parameter specifies the minimum number of receive buffers that are allocated. The
Total Receive Buffer Area for the adapter is calculated using the following formula:
Total Receive Buffer Area = MinRcvBuffs × RcvBuffSize
Note: To receive the maximum length frame that is supported by the attached network, the
Total Receive Buffer Area must be larger than the maximum frame size that is allowed for
the network, which is 4500 bytes for 4-Mbps Token Rings and 18 000 bytes for 16-Mbps and
100-Mbps Token Rings).
A smaller Total Receive Buffer Area will use less system memory but will correspondingly
reduce the size of the largest frame that can be received by the NDIS device driver. The
maximum frame size supported by the driver can be further limited by the MaxTxFrameSize
parameter.
Valid values: 1to512
The default is 20.
RcvBuffSize (OS/2 only) This parameter specifies the size of each receive buffer.
Valid values: 256 to 18 000
The default is 2252.
FullDuplex This parameter permits the device driver to activate token-ring full-duplex operation if
supported by the network. The MaxTxFrameSize parameter may need to be adjusted
separately, depending on network requirements.
Valid values:
Yes Permits full-duplex operation.
No Prohibits full-duplex operation.
The default is Yes.
54 IBM 16/4 Token-Ring PCI Management Adapter