System information

Troubleshooting Token Ring
Book Title
6-84
Ring speed
mismatch
Step 1 Check the ring speed specification on all nodes attached to the Token Ring backbone.
The ring speed configured for all stations must be the same (either 4 Mbps or
16 Mbps). Use the show running-config privileged exec command to determine
which speed is specified on the router.
Step 2 If necessary, modify ring speed specifications for clients, servers, and routers. On
routers, use the ring-speed interface configuration command to change the ring
speed.
Change jumpers as needed for modular router platforms that do not support software
speed configuration. For more information about ring speed specifications, refer to the
hardware installation and maintenance manual for your system.
Relay open in MAU
Step 1 If an “open lobe fault” message appears on the console at system power up, check the
cable connection to the MAU.
Step 2 Use the clear interface privileged exec command to reset the Token Ring interface
and reinsert the router into the ring.
For all Token Ring cards except the CTR and access routers, you must use the
clear interface command to reinitialize the Token Ring interface if the interface is
down.
Step 3 Use the show interfaces token exec command to verify that the interface and line
protocol are up.
Step 4 If the interface is operational, but the “open lobe fault” message persists and the
router still cannot connect to the ring, connect the router to a different MAU port.
Step 5 If the message continues to appear, disconnect all devices from the MAU and reset the
MAU’s relay with the tool provided by the MAU vendor.
Relay open
in MAU
Step 6 Reattach the router and determine whether it can connect to the ring. If resetting the
relay does not solve the problem, try replacing the MAU with one that is known to be
operational.
Step 7 If the router still cannot connect to the ring, check internal cable connections of the
router Token Ring cards. Ensure that cables associated with the respective port
numbers are correctly wired and that they are not swapped.
Step 8 If the router still cannot connect to the ring, replace the cables that connect the router
to the MAU with working cables.
Step 9 Use the clear interface command to reset the interface and reinsert the router into the
ring. Use the show interfaces token command to verify that the interface and line
protocol are up.
Step 10 Alternatively, you can connect the router to a spare MAU to which no stations are
connected. If the router can attach to the ring, replace the original MAU.
Duplicate MAC
2
address
This problem can arise when routers are using locally administered MAC addresses.
Step 1 Use a network analyzer to check the Duplicate Address test frames from a booting
station. If the station gets a response, then there is another station already configured
with the MAC address of the booting station.
Step 2 If there are two stations with the same MAC addresses, change the MAC address of
one of the stations and reinitialize the node.
Congested ring Step 1 Insert the router during an off-peak period.
Step 2 If insertion is successful during off-peak periods, but unsuccessful during peak load,
segment your internetwork to distribute traffic.
Media Problem Suggested Actions