Siemens Unix V4.0 - Manual (Page 242)

Troubleshooting Troubleshooting Procedures
Product Manual U7613-J-Z815-6-76
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Step 1: Verify the Status of the Physical Network
The first item to check is the physical network. The majority of today’s networking hardware
provides status indicators that can be used to assess the state of the various network links
(for example, 10-Base-T Hubs use LEDs). Always check these links for any signs of
problems with the physical network such as excessive re-transmissions, Link Integrity
mismatches, and jabber conditions.
Even in cases in which only a single client is affected, never assume that is it not a bad
cable connection. For a single client it is easy to check to determine whether the problem
occurs regardless of which server the client tries to use.
If a client cannot “see” anything on a network that is otherwise functioning without incident,
then it is safe to assume that the problem is related to that client’s network configuration. If
however, that same client can see other nodes on the network but cannot connect to a
particular server, then the network path to that server, the server itself, or the account being
used by that client are likely candidates for trouble.
There are several third-party products available that can be used to monitor the health of
the physical network. It is worthwhile to check network traffic periodically with one of these
devices to see whether there are problems occurring with the physical network.
Step 2: Verify the Transport Protocol Status
If the physical network appears to be functioning properly, the next step is to determine
whether the various computers on the network can “see” each other from the perspective
of a transport protocol. Most transport protocol applications include a connectivity test tool
that can be used to verify connectivity at the transport level between a client and the server
over the network.
If you cannot PING a server machine from a particular client, then neither will that client
computer be able to connect to the server. If you cannot PING a server from several client
computers, then one of the following conditions may be present: the server is not running,
the transport protocol is not running, or there is a configuration problem that is disrupting
network connectivity.
Review the recommendations in your transport protocol software documentation. If appro-
priate, continue with the procedures described later in this section on assessing the status
of the NetBIOS protocol and Advanced Server.
Step 3: Verify the NetBIOS Protocol Status
Check the NetBIOS protocol layer. Most NetBIOS modules provide test tools that test the
connectivity between NetBIOS names over the network.