Broadcasts allow TCP/IP to send certain types of messages, such
as alerts, to a wide audience on a LAN.
NetBIOS uses broadcasts for tasks such as name registration.
The following steps will help ensure that broadcasting is working
correctly, with the assumption that TCP/IP and NetBIOS are running on
both the local and remote machines. It should be possible to run the
local form of the nbstatus command on the local client
machine, and also on the remote machine if the nbstatus
command is available on that machine. The nbstatus command
with no arguments should return NetBIOS status information if NetBIOS is
running on the local machine.
Verify that the network and subnet portions of the IP
address are the same on all computers. Broadcasts do not repeat
across networks or subnets, so the network and subnet addresses must
be identical. The configuration of IP addresses varies
according to the specific implementation of TCP/IP. In SCO TCP/IP,
the local IP address is configured on the ifconfig
command line in the /etc/tcp file. You must reboot the
machine so that the changes made to /etc/tcp file take
effect. To configure the IP address in another
implementation of TCP/IP, refer to the documentation for that
implementation.
Verify that all computers on the network agree on either all ``0''s or
all ``1''s for the broadcast address. Using all ``1''s is recommended.
In SCO TCP/IP, the broadcast
address is specified on the ifconfig command line in the
/etc/tcp file by using 255 for each byte of the host portion
of the IP address. For example:
The network portion of the address in the preceding example is 10.0.118,
and the host portion is set to all ``1''s by appending 255 to the network
portion. If you change the /etc/tcp file, you must reboot
before the changes take effect.
Verify that all computers agree on the broadcast address relative to
the subnet mask. Some implementations of TCP/IP ignore the subnet
portion of class C IP addresses. If this
is a problem, replace the subnet number with the broadcast number when
defining the broadcast address. Using the same example as in step 2,
where the subnet portion is 118, the broadcast address would be
configured as follows:
If you change the broadcast address, reboot the machine to have the
changes take effect.
Verify that NetBIOS is working by using the form of the
nbstatus command that requests status
from a remote
computer. For example, to verify
that NetBIOS is working on the machine on your network named
fred, enter the command
nbstatus FRED
Note that the computer name is specified in all uppercase letters. If
NetBIOS is functioning between the two machines, a list of information
about the remote computer will be displayed. If an error is returned,
this indicates that NetBIOS is not working, either because
there is still a TCP/IP broadcast incompatibility, or because different
NetBIOS scope identifiers are being used.
Note that it is sometimes possible for the remote form
of the nbstatus command to return an error under normal
circumstances. Some implementations of NetBIOS do not accept the remote
adapter status NCB(Network Control Block);
also, if the remote machine
is a LAN Manager for UNIX Systems client, and there currently are no
sessions between the client and a server, then NetBIOS status is not
returned.