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READ.ME
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1993-08-30
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IBM TCP/IP for DOS.
RFC NetBIOS 2.1.0.1
I. General Description
NetBIOS is a protocol that allows both connection oriented and packet
oriented communication. The original NetBIOS (referred to as native NetBIOS)
is only available between machines on the same local area network. RFC NetBIOS
is a standard (defined by RFCs 1001 and 1002) that implements the NetBIOS
interface while taking advantage of TCP/IP protocols. The advantage is that
it allows programs that use NetBIOS to communicate across any internet.
II. Executable Descriptions
NBTCP.EXE -- the executable that installs the RFC NetBIOS in memory.
It takes about 35K of DOS memory and approximately 1.5M
of protected mode memory. Because of its protected memory
requirement, it may be necessary to increase the
VCPI_reserve value. Allocate at least 1,500,000 for NBTCP
alone. More will be required by other programs.
NBTCP can be run either by TCPSTART (configurable in
the CUSTOM.EXE program with the TCP/IP for DOS base kit)
or just typing NBTCP.EXE from the DOS prompt. NBTCP must
be run before you start additional windowing operating
systems from DOS.
NBDOWN.EXE -- this executable removes RCF NetBIOS from memory.
RFC NetBIOS is limited the same way most TSRs are, in that
any TSRs installed after it must be removed before you
can remove the NetBIOS program.
MAPNAME.EXE -- a utility that converts between RFC Encoded and NetBIOS
names. CSD 2.1.0.1 allows redirection of input and output
to files.
III. Configuration Parameters
RFC NetBIOS can be configured by adding parameters to your TCPDOS.INI
file in you ETC directory. The parameter name and value must be on
the same line and be seperated by an equal sign. Preceeding spaces do not
matter. You are not required to configure all the parameters for RFC NetBIOS
to work properly, if they are not present RFC NetBIOS will use the default
values.
A. Network parameters
These parameters define what adapter RFC NetBIOS uses and which NDIS
interface. These must be set if you wish to cohabitate with native
NetBIOS on the same machine.
nb.adapter This parameter determines which adapter to use
and must be set. It expects either the NDIS
adapter number or the SLIP number (i.e. ND0 or SL0).
The adapter number is mapped to a physical adapter
inside CUSTOM.EXE
nb.lana_num This defines the LAN interface we will use if
we wish to cohabitate with native NetBIOS. It
defaults to 0.
B. Name parameters
Since NetBIOS names do not have any relation to IP addresses or machine
names (you may use the same names to avoid confusion, but you don't
have to), RFC NetBIOS has three methods of determining which specific
machine your NetBIOS application is referring to. You may have a names
file which maps NetBIOS names either directly IP addresses or to IP names
that can be resolved with the domain name server. RFC NetBIOS may also
broadcast for the name, querying everyone on its own LAN and everyone in
its broadcast file to see if they are that name. Finally, it can access
the Domain Name Server (DNS) directly to ask for an IP address.
nb.search_order This defines the order in which RFC NetBIOS will
attempt to resolv a NetBIOS name. It may any
of the characters N, B and D in any order or
combination. It makes no sense to repeat a
letter, however. N specifies the names file.
B specifies broadcast (which includes the local lan
and any entries in the broadcast file). D specifies
DNS. The default is NB (NBTCP will check the names
file and if it can't find it there, broadcast
for it.)
nb.names_file This sets the file to be used as your names file.
This maps NetBIOS names to IP addresses or IP
machine names. It is the fastest method for RFC
NetBIOS to resolve NetBIOS encoded names. If you
only connect to one machine, or have one machine
machine (say a file server) that is frequently
accessed, you will probably want to put it in here
to save time in trying to locate it. It defaults
to names.nb in your ETC directory.
nb.broadcast_file This defines what file in you ETC directory is
your broadcast file. When RFC NetBIOS broadcasts
for a name, it sends queries to every machine
on its own LAN and every machine in its broadcast
file looking for the name. You may specify an
entire network by putting in that networks
broadcast address rather than a specific machine
name. It defaults to broadcast.nb in your ETC
directory.
Broadcast Parameters
These parameters only have meaning if you use broadcasting to resolve
your NetBIOS names. (i.e. you have a B in your nb.search_order)
nb.retries The RFC NetBIOS standard uses UDP for names on the
network. Since UDP is not a guaranteed delivery
protocol, we send each UDP packet multiple times.
The RFC establishes 3 retries as the standard.
It is configurable between 1 and 10.
nb.retry_delay RFC 1002 establishes 250 milliseconds as the
delay between UDP sends. This parameter is
measured in millisecond increments. It is
configurable from 10 - 2000 (10ms to 2s).
nb.conflict_delay After RFC NetBIOS receives a positive response
to a name search, it must wait a specified amount
of time in case another machines also claims that
name and causes a conflict. RFC 1002 establishes
1 second as the standard. This parameter is
measured in millisecond increments and is
configurable from 100 - 2000 (100ms to 2s).
C. Other configuration parameters
General rule: don't play with these unless you really need to.
nb.max_sockets This parameter determines the maximum number
of file handles available to RFC NetBIOS.
It may be between 8 and 50. This parameter is
provided for very specialized applications and
should not be modified unless necessary.
nb.max_recv_buffers Sets the maximum number of receive buffers RFC
NetBIOS should allocate at init time. This number
should only be changed if needed. The acceptable
range is 4 to 20 and defaults to 15.
IV. Common Problems
One of the common problems discovered in testing is the sensitivity of
various programs to the name broadcasts of RFC NetBIOS. (This is not
a problem if you're not using broadcasting to resolve names.) Most NetBIOS
applications are expecting native NetBIOS and the fast response of a LAN.
Due to its nature, and the unreliability of UDP packets, RFC NetBIOS requires
a slower protocol. If your NetBIOS applications often report errors to
you when trying to contact a station, you may want to try decreasing the
retry_delay or the conflict_delay slightly. On a small network with limited
traffic, it may also be safe to lower the retries to 2. These options
should be handled with care however and modified only as much as absolutely
necessary. These parameters affect mostly name operations, and not session
performance at all. Changing these cannot improve session performance, only
the speed in which it locates names (i.e only during an initial login, but not
during subsequent transfers).
A better alternative is to put the host name directly in your names file
and specify N before B in you search order. This may not be convenient
however if you contact a wide variety of machines.