4.5 DXMT0MOD.SYS Adapter Transmit and Receive Buffer Default Sizes
When the adapter is opened by NetBIOS (DXMT0MOD.SYS), transmit and receive
buffer sizes of the adapter are determined by NetBIOS, unless specifically
overridden. The adapter type and the number of link stations are used to
determine these values, as shown in the following table.
Note: The Data Holding Buffer (DHB) = the adapter transmit buffer size.
The Number of DHBs (DHB.NUMBER) = the number of transmit buffers.
+------------------------------------------------------------------------+
| Figure 4-6. IBM NDIS Adapter |
+-----------------+------------------+-----------------+-----------------+
| | | Transmit | |
| Number of Link | Number of | Buffers in | Receive Buffers |
| Stations | Transmit Buffers | Bytes | in Bytes |
+-----------------+------------------+-----------------+-----------------+
| 1 to 32 | 2 | 4192 | 280 |
+-----------------+------------------+-----------------+-----------------+
| 33 to 48 | 2 | 4192 | 280 |
+-----------------+------------------+-----------------+-----------------+
| 49 to 64 | 1 | 4192 | 280 |
+-----------------+------------------+-----------------+-----------------+
| More than 64 | 2 | 2040 | 280 |
+-----------------+------------------+-----------------+-----------------+
4.6 DXMT0MOD.SYS Determination of Session Data Transmit Frame Size
When a session is established between two NetBIOS nodes, the length of the
largest data frame sent between the two sessions is determined by three
factors:
1. The size of the sender's transmit buffer
2. The amount of receive-buffer space in the receiver
3. The maximum frame that can pass any bridge in the path.
On each side (node) the receive-buffer space calculation is made in the
following way:
° The number of receive buffers is calculated.
° One-half of the number of receive buffers is multiplied by the data
size of one buffer. This determines the maximum size frame that can
be transmitted to the session. The purpose of this is to ensure that
one adapter can hold two maximum-size received frames.
4.7 Parameters for DXMJ0MOD.SYS
Many parameters are available to customize DXMJ0MOD.SYS, which is the
NetBIOS protocol driver for NDIS MAC drivers.
4.7.1 Network Adapter Address Configuration
For specification of a locally administered address for an NDIS MAC driver
that is bound to DXMJ0MOD.SYS, the address must be configured in the MAC
section of the PROTOCOL.INI file. This address must consist of 12
hexadecimal digits enclosed by double quotation marks, for example,
"400000000001". To use the Installation Aid to enter this value, go to
the panel that enables you to change the adapter driver parameters.
Using this method with DXME0MOD.SYS, instead of using the ADDR parameter,
is recommended in all configurations and is required when more than one
NDIS protocol stack is used. With this method, the locally administered
address specified in PROTOCOL.INI will be used no matter which protocol
stack opens the adapter first.
For example, if your adapter is a Streamer Family adapter, the NDIS MAC
driver name is IBMMPC.DOS. The module name that identifies the MAC named
section in PROTOCOL.INI is IBMMPC_MOD. Put the value of the address equal
to the keyword NETADDRESS in [IBMMPC_MOD], as shown in the following
example:
[IBMMPC_MOD]
DriverName = IBMMPC$
NETADDRESS = "400000000001"
4.7.2 Editing Parameters for DXMJ0MOD.SYS
If possible, use the Installation Aid to change these parameters. If you
do change these values manually, edit PROTOCOL.INI. Parameter values
placed in PROTOCOL.INI override the default values.
The parameters in PROTOCOL.INI are in the form Keyword = Value. Each
parameter must be on a separate line in the [DXMJ0MOD_MOD] section. The
parameters can be in any order.
The following example shows the [DXMJ0MOD_MOD] section of PROTOCOL.INI
before configuration:
[DXMJ0MOD_MOD]
DriverName = NETBEUI$
Bindings =
To edit this file, add the keyword and its value on a separate line. Each
line should come after Bindings =. If PROTOCOL.INI is set up to bind the
adapter using IBMMPC.DOS, and if a value of 18 is added for SESSIONS, the
[DXMJ0MOD_MOD] section of PROTOCOL.INI looks like this:
[DXMJ0MOD_MOD]
DriverName = NETBEUI$
Bindings = IBMMPC_MOD
SESSIONS = 18
For more information about manual configuration of NDIS adapters, see
Chapter 3, "Configuring the LAN Support Program NDIS Manually."
4.7.3 Keyword Values for DXMJ0MOD.SYS
Figure 4-7 shows the keywords and their default values for the NetBIOS
protocol driver for NDIS MAC drivers (DXMJ0MOD.SYS).
+------------------------------------------------------------------------+
| Figure 4-7. NetBIOS Protocol Driver for NDIS MAC Drivers |
| (DXMJ0MOD.SYS) Keyword Values |
+------------------------------------------+-----------+-------+---------+
| | | Mini- | |
| | Valid | mum | Default |
| Keyword | Values | Value | Value |
+------------------------------------------+-----------+-------+---------+
| | I (IEEE | | |
| | 802.3) / | | |
| | D (DIX | | I (IEEE |
| ETHERAND_TYPE | 2.0) | - | 802.3) |
+------------------------------------------+-----------+-------+---------+
| | Y (Yes) | | |
| USEADDRREV | N (No) | - | Yes |
+------------------------------------------+-----------+-------+---------+
| SESSIONS | 1 to 254 | 1 | 16 |
+------------------------------------------+-----------+-------+---------+
| NCBS | 1 to 255 | 1 | 15 |
+------------------------------------------+-----------+-------+---------+
| NAMES | 2 to 254 | 2 | 21 |
+------------------------------------------+-----------+-------+---------+
| | Y (Yes) | | |
| USEMAXDATAGRAM | N (No) | - | No |
+------------------------------------------+-----------+-------+---------+
| | 0 to | | |
| ADAPTRATE | 65 535 | 0 | 1000 |
+------------------------------------------+-----------+-------+---------+
| WINDOWERRORS | 0 to 10 | 0 | 0 |
+------------------------------------------+-----------+-------+---------+
| | 512 to | | |
| STACKSIZE | 4096 | 512 | 2048 |
+------------------------------------------+-----------+-------+---------+
| | 1000 to | | |
| TI | 65 535 | 1000 | 30000 |
+------------------------------------------+-----------+-------+---------+
| | 50 to | | |
| T1 | 65 535 | 50 | 1000 |
+------------------------------------------+-----------+-------+---------+
| | 50 to | | |
| T2 | 65 535 | 50 | 200 |
+------------------------------------------+-----------+-------+---------+
| MAXIN | 1 to 127 | 1 | 1 |
+------------------------------------------+-----------+-------+---------+
| MAXOUT | 1 to 127 | 1 | 1 |
+------------------------------------------+-----------+-------+---------+
| | 500 to | | |
| NetBIOSTIMEOUT | 10 000 | 500 | 500 |
+------------------------------------------+-----------+-------+---------+
| NetBIOSRETRIES | 1 to 50 | 1 | 8 |
+------------------------------------------+-----------+-------+---------+
| NAMECACHE | 0 to 255 | 0 | 0 |
+------------------------------------------+-----------+-------+---------+
| PIGGYBACKACKS | 0/1 | - | 1 |
+------------------------------------------+-----------+-------+---------+
| LOOPPACKETS | 1 to 1000 | 1 | 1 |
+------------------------------------------+-----------+-------+---------+
| DATAGRAMPACKETS | 2 to 1000 | 2 | 2 |
+------------------------------------------+-----------+-------+---------+
| PACKETS | 1 to 1000 | 1 | 50 |
+------------------------------------------+-----------+-------+---------+
| PIPELINE | 1 to 200 | 1 | 20 |
+------------------------------------------+-----------+-------+---------+
| | 512 to | | |
| MAXDATARCV | 16 384 | 512 | 4168 |
+------------------------------------------+-----------+-------+---------+
| | 1 to | | |
| MAXTRANSMITS | 10 000 | 1 | 6 |
+------------------------------------------+-----------+-------+---------+
| MINTRANSMITS | 0 to 9999 | 0 | 2 |
+------------------------------------------+-----------+-------+---------+
| | 1 to | | |
| DLCRETRIES | 65 535 | 1 | 8 |
+------------------------------------------+-----------+-------+---------+
| LANABASE | 0 to 254 | 0 | 0 |
+------------------------------------------+-----------+-------+---------+
4.7.4 Keyword Parameter Descriptions for the NetBIOS Protocol Driver for NDIS Adapters (DXMJ0MOD.SYS)
ETHERAND_TYPE
° Specifies the default protocol conventions to use when the
NetBIOS protocol is bound to an Ethernet network adapter
driver that supports both IEEE 802.3 and DIX 2.0
conventions.
° Must be specified as either I (IEEE 802.3) or D (DIX 2.0).
° If omitted, the default is I (IEEE 802.3).
USEADDRREV
° Specifies whether the address used for the universally
administered address and NAME_NUMBER_1 is reversed.
° Must be specified as either Y (Yes) or N (No).
° If set to Y, the universally administered address used in
the ADAPTER_STATUS command and in NAME_NUMBER_1 will be
byte-reversed (that is, if the address is X'010203040506',
it will be saved as X'060504030201').
° If omitted, the default is Y.
SESSIONS
° Specifies the maximum number of NetBIOS sessions that can be
open simultaneously. The NetBIOS protocol uses a session
each time it adds or finds a NetBIOS name.
° Increase the value of this parameter if ADD.NAME or
FIND.NAME requests occur simultaneously.
° If a request fails because of a lack of sessions, the
protocol returns an interface-busy error.
° Must be a decimal number from 1 to 254.
° If omitted, the default is 16.
NCBS
° Specifies the number of network control block (NCB)
descriptors to allocate for managing NCBs submitted to the
NetBIOS protocol.
° Must be a decimal number from 1 to 255.
° If omitted, the default is 15.
NAMES
° Specifies the maximum number of NetBIOS names that can be
defined. One name is reserved for defining the station
address of the network adapter. If the NetBIOS protocol is
bound to multiple network adapter drivers, this parameter
specifies the maximum number of NetBIOS names in the name
table of each network adapter driver.
° Must be a decimal number from 2 to 254.
° If omitted, the default is 21.
USEMAXDATAGRAM
° Specifies whether to request the full transmit buffer size
for datagrams.
° Must be specified as either Y (Yes) or N (No).
° If set to N, the length of a datagram has a maximum of 512
bytes. If this parameter is set to Y, the full transmit
buffer size is used for datagrams.
° If omitted, the default is N.
ADAPTRATE
° Specifies the time, in milliseconds, between runs of the
adaptive window algorithm. For each link, the NetBIOS
protocol uses the adaptive window algorithm to change the
Maximum Receives Outstanding and Maximum Transmits
Outstanding parameter values to match the values set on the
remote workstation.
° Must be a decimal number from 0 to 65 535.
° If 0, the algorithm is turned off.
° If omitted, the default is 1000.
WINDOWERRORS
° Specifies the number of dropped packets that the adaptive
window allows before decreasing the Maximum Transmits
Outstanding parameter value. Increase the value of this
parameter on a network with a heavy workload. Decrease the
value of this parameter on a network with a light workload.
° Must be a decimal number from 0 to 10.
° If omitted, the default is 0.
STACKSIZE
° Specifies the internal stack space used when called by the
timer interrupt, receive interrupt, or NCB interrupt.
° Must be a decimal number from 512 to 4096.
° If omitted, the default is 2048.
TI
° Specifies the inactivity timer value in milliseconds. The
inactivity timer determines how often the NetBIOS protocol
checks an inactive link to verify that the link is still
operational. To minimize unnecessary link checks, it is
recommended that this parameter be set to the default of
30 000 milliseconds.
° Must be a decimal number from 1000 to 65 535.
° If omitted, the default is 30 000.
° For more information, refer to the Response Timer (T1)
parameter.
T1
° Specifies the transmission timer value for NetBIOS links and
determines, in milliseconds, the delay before transmitting a
link-level frame again if no acknowledgment is received.
The three timer parameters must have the following
relationship: T2 < T1 <TI. The T1 parameter value should be
approximately two to five times the T2 parameter value.
° Must be a decimal number from 50 to 65 535.
° If omitted, the default is 1000.
T2
° Specifies the delayed acknowledgment timer value and
determines, in milliseconds, the length of the delay before
acknowledging a received frame, when the number of frames
received is less than the Maximum Receives Outstanding
parameter value.
° Must be a decimal number from 50 to 65 535.
° If omitted, the default is 200.
MAXIN
° Specifies the number of NetBIOS message packets to receive
before sending an acknowledgment.
° The Maximum Receives Outstanding parameter value should be
less than or equal to the Maximum Transmits Outstanding
parameter value.
° Must be a decimal number from 1 to 127.
° If omitted, the default is 1.
MAXOUT
° Specifies the number of NetBIOS message packets to send
before expecting an acknowledgment.
° The Maximum Transmits Outstanding parameter value should be
greater than the Maximum Receives Outstanding parameter
value.
° Must be a decimal number from 1 to 127.
° If omitted, the default is 1.
NetBIOSTIMEOUT
° Specifies the time, in milliseconds, that the NetBIOS
protocol waits between transmission attempts.
° Must be a decimal number from 500 to 10 000.
° If omitted, the default is 500.
° For more information, refer to the NetBIOSRETRIES parameter.
NetBIOSRETRIES
° Specifies the number of times the NetBIOS protocol attempts
transmissions at the NetBIOS level before assuming that the
receiver is not present. The transmission activities
include name claims, session setups, and other similar
actions.
° Must be a decimal number from 1 to 50.
° If omitted, the default is 8.
° For more information, refer to the NetBIOSTIMEOUT parameter.
NAMECACHE
° Specifies the number of remote names that the workstation
contacts.
° If set to 0, the remote name directory is not used. The
remote name directory reduces the number of frames broadcast
to the NetBIOS functional address on the network. The
remote name directory sends a frame to a specific node
whenever possible.
° Must be a decimal number from 0 to 255.
° If omitted, the default is 0.
PIGGYBACKACKS
° Specifies whether the NetBIOS protocol sends and receives
acknowledgments piggybacked with incoming data.
° Must be either 0 or 1.
° If set to 1, the workstation sends and requests piggybacked
acknowledgments. If this parameter is set to 0, the
workstation neither sends nor requests piggybacked
acknowledgments.
° If omitted, the default is 1.
LOOPPACKETS
° Specifies the number of internal loop-back packet
descriptors. Loop-back packets are used when sending
I-frames or UI-frames, if the sending node and the receiving
node are the same.
° Must be a decimal number from 1 to 1000.
° If omitted, the default is 1.
DATAGRAMPACKETS
° Specifies the number of data descriptors to allocate for
packeting NetBIOS datagrams into UI-frames. Increase this
parameter value when the NetBIOS protocol sends a large
number of datagrams.
° Must be a decimal number from 2 to 1000.
° If omitted, the default is 2.
PACKETS
° Specifies the number of I-frame packet descriptors that the
NetBIOS protocol can use to build DLC frames from NetBIOS
messages. Increase the value of this parameter if large
frames are being sent through the network.
° Must be a decimal number from 1 to 1000.
° If omitted, the default is 50.
PIPELINE
° Specifies the number of NetBIOS message packets that are
prebuilt and waiting in a pipeline for each session.
Increase the value of this parameter if long streams of
packets are usually sent. Decrease the value of this
parameter if short, occasional groups of packets are sent.
° Must be a decimal number from 1 to 200.
° If omitted, the default is 20.
MAXDATARCV
° Specifies, in bytes, the maximum receive data size. This is
the maximum size of the user data in any frame that this
node will receive on a session. The session partner will
limit the size of the user data in frames transmitted over
the session to this size or to the size available in its
transmit buffer, whichever is smaller. NetBIOS takes into
account the maximum size that bridges in the path will
forward. It will never send a frame larger than what the
bridge will forward.
° Must be a decimal number from 512 to 16 384.
° If omitted, the default is 4168.
MAXTRANSMITS
° Specifies the number of packets that the NetBIOS protocol
can send at once to an NDIS MAC driver. The NetBIOS
protocol queues the packets internally when this parameter
value is low. The NDIS MAC driver must queue the packets
when this parameter value is high.
° Must be a decimal number from 1 to 10 000.
° If omitted, the default is 6.
MINTRANSMITS
° When a network adapter driver returns an out-of-resource
condition, the NetBIOS protocol stops sending packets. This
parameter specifies the number of transmission confirmations
the NetBIOS protocol must receive from the network adapter
driver before sending additional packets. This value should
be less than the Maximum Transmits parameter value.
° Must be a decimal number from 0 to 9999.
° If omitted, the default is 2.
DLCRETRIES
° Specifies the number of additional transmission attempts
that the NetBIOS protocol makes before assuming that the DLC
layer of the receiving workstation is not responding. The
value of this parameter can be low on a reliable network
that does not drop many packets. Increase this parameter
value on a network that drops a large number of packets.
° Must be a decimal number from 1 to 65 535.
° If omitted, the default is 8.
LANABASE
° Specifies the base number for the primary adapter. For
example, if this parameter is set to 3, the primary adapter
is identified as adapter 3 and the alternate adapter as
adapter 4. If the default of 0 is used, the primary adapter
is adapter 0 and the alternate adapter is adapter 1.
° Must be a decimal number from 0 to 254.
° If omitted, the default is 0.
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