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Customer Support Bulletin

Product: 1108FX-A(DJ1404042), 1216FX-A(DJ1404031), 1216TF-A(DJ1404032)

Description:

This Customer Support Bulletin contains information regarding issues with Accelar modules that use the new MT-RJ transceivers for the 100BASE-FX interfaces. The Accelar modules with MT-RJ transceivers for the 100BASE-FX interfaces may indicate false link and transmit and receive activity when the dust covers are in place.

Discussion: The MT-RJ 100BASE-FX transceiver appears to have a cross talk problem between the transmit and receive channels only when the dust cover is in place - the FX ports operate correctly when properly cabled/connected to another device. Switch performance can be impacted if the Spanning Tree Protocol is enabled during this cross talk condition.

The following symptoms will confirm that customers have this issue with their MT-RJ 100BASE-FX ports:

• The 100BASE-FX port LEDs will be a steady flashing green.
• The 100BASE-FX ports may indicate consistent Link Up/Down status in the System Log (see Figure 1.).
• If the Spanning Tree Protocol has been enabled on the system, the changing Link Up/Down status may cause STP topology changes to be recorded in the System Log (see Figure 1.).
• The data transmit and receive counters will also increment during this condition(see Figure 2.).

Figure 1.

Accelar-1200# show log file tail

Figure 2.

ExcessiveCollisions: 0

Resolution: The unused FX ports should be disabled via the management interface and MT-RJ cables should be installed on the ports to provide dust protection. Disabling the unused ports will stop messages going to the system log, will no longer increment the interface statistics, and will also stop Spanning Tree Topology Changes. However the port LEDs will continue to flash. To stop the LEDs from flashing and provide dust protection, replace the dust covers with MT-RJ cables.

The following CLI command will disable port 1 on slot 1 and confirms the change occurred.

Locked: false