Media Problems Token Ring

Table 6-1 outlines problems commonly encountered on Token Ring networks and offers general guidelines for solving those problems.

Table 6-1 Media Problems: Token Ring

Media Problem Suggested Actions

Table 6-1 Media Problems: Token Ring

Media Problem Suggested Actions

Nonfunctional

Step 1

Use the show interfaces token command to determine the status of the router's

Token Ring

Token Ring interfaces.

Step 2

If the status line indicates that the interface and line protocol are not up, check the cable from the router to the MAU.1 Make sure that the cable is in good condition. If it is not, replace it.

Step 3

If you are performing a new installation, make sure that the MAU has been properly initialized. For information on initializing your MAU, refer to the manufacturer's documentation.

Media Problem Suggested Actions

Ring speed mismatch

Relay open in MAU

Relay open in MAU

Duplicate MAC2 address

Congested ring

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.

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.

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.

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.

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.

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.

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.

Step 7

Step 8

Media Problem Suggested Actions

RPS3 conflict

Step 1

Use the no lnm rps interface configuration command to disable the RPS function on the router that you are trying to insert into the ring.

Step 2

Try to insert the router into the ring.

Step 3

If you can insert the router with RPS disabled, there is a conflict between RPS implementations. Contact your technical support representative for more information.

1 MAU = multistation access unit

2 MAC = Media Access Control

3 RPS = Ring Parameter Server

1 MAU = multistation access unit

2 MAC = Media Access Control

3 RPS = Ring Parameter Server show interfaces tokenring

When troubleshooting Token Ring media in a Cisco router environment, you can use the show interfaces tokenring command to provide several key fields of information that can assist in isolating problems. This section provides a detailed description of the show interfaces tokenring command and the information it provides in Table 6-2.

Use the show interfaces tokenring privileged exec command to display information about the Token Ring interface and the state of source route bridging:

show interfaces tokenring unit [accounting]

show interfaces tokenring slot | port [accounting] (for the Cisco 7500 series and Cisco 7200 series)

show interfaces tokenring [slot | port-adapter | port] (for ports on VIP cards in the Cisco 7500 series routers)

Was this article helpful?

0 0
The Ultimate Computer Repair Guide

The Ultimate Computer Repair Guide

Read how to maintain and repair any desktop and laptop computer. This Ebook has articles with photos and videos that show detailed step by step pc repair and maintenance procedures. There are many links to online videos that explain how you can build, maintain, speed up, clean, and repair your computer yourself. Put the money that you were going to pay the PC Tech in your own pocket.

Get My Free Ebook


Post a comment