System information
Troubleshooting IBM
Book Title
10-224
RSRB: Periodic Communication Failures
Symptom: Communication failures occur periodically 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 10-5 RSRB: Periodic Communication Failures
End system
misconfiguration
Step 2 Check the command output for the MAC address of the workstation or server. If
the MAC address is not present in the output, check the configuration of the end
system.
Step 3 If the problem persists, use a network analyzer to check network traffic generated
by the end system. If you do not have a network analyzer, use the debug
token-ring and the debug source-bridge commands.
Caution: Using the debug token-ring and the debug source-bridge commands
on a heavily loaded router is not advised. These commands can cause further
network degradation or complete network failure if not used judiciously.
Step 4 Check the output of the debug commands to see whether the end system is sending
traffic to the correct MAC addresses or destination names (in the case of
NetBIOS).
End system does
not support RIF
Step 1 Place a network analyzer on the same ring to which the end system is connected.
Step 2 Look for RIF frames sent from the end system (RIF frames have the high-order bit
of the source MAC address set to 1).
Step 3 If no RIF frames are seen, the end system does not support RIF and cannot
participate in source routing.
If the protocol is routable, you can route the protocol or configure transparent
bridging. If you use transparent bridging, be careful not to create loops between the
SRB and the transparent bridging domains.
Step 4 If your environment requires SRB, contact your workstation or server vendor for
SRB drivers or for information about setting up your workstation or server to
support SRB.
Explorer traffic
not reaching remote
ring
Step 1 Using a network analyzer or the debug source-bridge command, watch network
traffic to see whether explorers from the end system reach the remote ring.
Step 2 If traffic reaches the remote ring successfully, check the configuration of the
destination end system (for example, a server) to see why that station does not
reply to the explorer traffic from the source.
If traffic does not reach the remote ring, use the show source-bridge command to
check ring lists. If information about the ring has not been learned, check router
configurations.
Step 3 If you are using NetBIOS, use the show netbios name-cache exec command to see
whether traffic is passing through the network properly. If it is not, check router
configurations.
For detailed information about configuring routers for RSRB, refer to the Cisco IOS
Bridging and IBM Networking Configuration Guide and Bridging and IBM Networking
Command Reference.
1 LNM = LAN Network Manager
Possible Problem Solution