System information

Troubleshooting IBM 10-225
RSRB: NetBIOS Client Cannot Connect to Server
RSRB: NetBIOS Client Cannot Connect to Server
Symptom: NetBIOS clients cannot connect to NetBIOS servers over a router configured as an
RSRB.
Table 10-6 outlines the problems that might cause this symptom and describes solutions to those
problems.
Table 10-6 RSRB: NetBIOS Client Cannot Connect to Server
Possible Problem Solution
Misconfigured
T1 timers
If you are not using local acknowledgment, misconfigured T1 timers can cause periodic
timeouts.
Step 1 Use a network analyzer to see how long it takes for packets to travel from one end
of the network to the other.
Step 2 Use a ping test to the remote router and note the round-trip delay. Compare this
value with the configured T1 timer values on end systems.
Step 3 If the round-trip delay is close to or exceeds the T1 timer value, acknowledgments
are probably being delayed or dropped by the WAN. For delays, increase the T1
configuration on end systems. For drops, check buffers and interface queues.
Step 4 Enable local acknowledgment to see whether that solves the problem.
WAN link problem For information on troubleshooting serial line problems, refer to Chapter 15,
“Troubleshooting Serial Line Problems.” For information on troubleshooting different
WAN environments, refer to the appropriate chapter elsewhere in this book.
Possible Problem Solution
Incorrect mapping of
NetBIOS name cache
server-to- client
mapping
Step 1 For each router on which NetBIOS name caching is enabled, use the show rif exec
command to determine whether the RIF entry shows the correct path from the
router to both the client and the server.
The following is an example of the show rif exec command:
cantatrice#show rif
Codes: * interface, - static, + remote
Hardware Addr How Idle (min) Routing Information Field
5C02.0001.4322 rg5 - 0630.0053.00B0
5A00.0000.2333 TR0 3 08B0.0101.2201.0FF0
5B01.0000.4444 - - -
0000.1403.4800 TR1 0 -
0000.2805.4C00 TR0 * -
0000.2807.4C00 TR1 * -
0000.28A8.4800 TR0 0 -
0077.2201.0001 rg5 10 0830.0052.2201.0FF0
In this display, entries marked with an asterisk (*) are the router’s interface
addresses. Entries marked with a dash (-) are static entries. Entries with a number
denote cached entries. If the RIF timeout is set to something other than the default,
15 minutes, the timeout is displayed at the top of the display.
Step 2 Use the show running-config privileged exec command to view the router
configuration. Make sure that the source-bridge proxy-explorer interface
configuration command is included in the Token Ring configuration. Proxy
explorers must be enabled on any interface that uses NetBIOS name caching.
Step 3 Use the show netbios-cache exec command to see whether the NetBIOS cache
entry shows the correct mappings of server and client names to MAC addresses.