Table of Contents

Troubleshooting Ethernet, ATM Uplink, and POS Uplink Interfaces

This chapter provides troubleshooting information about connectivity and performance problems in the Ethernet, ATM uplink, and POS uplink physical interfaces of a Layer 3 enabled ATM switch router.

The chapter includes the following sections:

Troubleshooting General Ethernet Interface Problems

You might see problems of cell transmission through the switch router, detected by a buildup of cells on an internal virtual channel (VC). These problems occur for the following reasons:

Troubleshooting Switch Card Failures

A switch processor can have a cell stuck problem in internal virtual channels (VCs), resulting from timing issues in the hardware and software on the Catalyst 8540 CSR. You might see more than one port affected on one or more interface modules. Online insertion and removal (OIR) of the interface module will temporarily fix the problem.

Follow these steps to troubleshoot cell stuck problems:

        Rejected Cells: 0

        Invalid Cells: 1616700

The show switch fabric command clears the counters after it displays. Entering the command again shows the current activity on the switch router.

Step 2   Issue the show switch fabric command again to show new activity.

        Rejected Cells: 2189

        Invalid Cells: 58

Look at the values in the Rejected Cells and Invalid Cells fields. Note that the Rejected Cells and Invalid Cells field counters are increasing. This means there might be a problem in the switch fabric.

Step 3   Verify that no ports are involved by issuing the show epc queuing and show epc status commands.

If the queues are empty and all of the ports show OK status, then the problem is not the ports, it is the switch processor.

You can resolve this problem by upgrading your system software image to release Cisco IOS Release version 12.0(4a)WX5(11) or later, by replacing the switch processors, or by doing both.

Troubleshooting Port Stuck Problems

If one or more Fast Ethernet or Gigabit Ethernet ports are not transmitting cells, then the failure might be a port stuck problem.

Follow these steps to troubleshoot a port stuck problem:

Note   Be sure to use the show switch fabric command during the lightest possible traffic conditions because actual traffic might be using the memory buffers.

     Rejected Cells: 389023

        Invalid Cells: 56399

The show switch fabric command clears the counters after it displays. Entering the command again shows the current activity on the switch router.

Step 2   Enter the show switch fabric command again.

     Rejected Cells: 2189

        Invalid Cells: 58

Look at the values in the Rejected Cells and Invalid Cells fields. Note that the Rejected Cells and Invalid Cells field counters are increasing. This means there might be a problem in the switch fabric.

Step 3   Use the show epc queuing and show epc status command to display interface queues and status.

Status of GigabitEthernet1/0/0: not OK

The show epc queuing command output shows that no activity is going across interface GigabitEthernet 1/0/0. This is verified in the show epc status command output, which indicates that interface GigabitEthernet 1/0/0 is "not OK." You have confirmed that the problem is a stuck port.

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Note    You might see a few cells in the QCNT column in the show epc queuing command output. That is normal. Issue the command several times to verify that traffic is moving through the queues. If the QCNT column values are incrementing and incrementing for the VCIs belonging to a particular interface, the problem is probably a stuck port.

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You can remedy the port stuck condition by removing and reinserting the interface module. A shutdown/no shutdown command sequence on the problem interface does not resolve the problem.

Configuring Automatic Port Stuck Failure Recovery

To recover from a port stuck failure, perform the following tasks:

If the switch router is not configured to reset the port upon detecting a port stuck failure, the port will be isolated, thus preserving the integrity of the switch router.

If the switch router is configured to reset the port upon detection of a stuck port failure, the switch router will isolate the port from the rest of the functioning ports, and reset the port. This might affect other ports on the interface module.

Note   If you configure the switch router as described in the nondefault behavior section after a port stuck failure is detected, the switch router will not reset the Ethernet ports. The Ethernet interface must be configured to reset before the port stuck failure occurs. Also, the default behavior is to not reset the port if a port stuck failure is detected. If the Ethernet interface is not configured to reset when a port stuck failure is detected, schedule the switch router for downtime to remove and reinsert the module.

To configure the switch router to automatically recover from port stuck failures, use the following interface configuration commands:

Caution   Because of the nature of the microcode architecture, do not configure low values for the wait time in the epc portstuck-wait command. The default value of 180 seconds has been carefully chosen, allowing for the hello intervals of protocols such as HSRP, EIGRP, and OSPF. Configuring a low value might lead to incorrectly detecting temporary port stuck failures as real port stuck failures, and can cause a temporary loss of connectivity. It is highly recommended to keep this value to at 60 seconds, at a minimum. Lower values are provided to allow for some specific network designs when you can absolutely rule out temporary port stuck failure scenarios, and also as a debugging aid. For most networks, 180 seconds works very well.

Connectivity Troubleshooting Commands

To troubleshoot a connectivity problem between a port and another port or end-station, use the following commands:

Troubleshooting 10/100 Ethernet Interface Modules

This section describes specific processes and commands used to troubleshoot the 10/100BASE-T and BASE-FX Ethernet interface modules.

The Catalyst 8500 CSR supports two different interface modules. The 10/100BASE-T Ethernet interface module supports 100-Mbps Layer 2 or Layer 3 UTP connections. The 100BASE-FX Ethernet interface module supports 100-Mbps Layer 2 or Layer 3 multimode fiber connections.

This section includes the following:

10/100BASE-T Interface Modules

The 10/100BASE-T Ethernet interface module supports 16 10-Mbps or 100-Mbps Layer 2 or Layer 3 unshielded twisted-pair (UTP) ports. This module supports full-duplex or half-duplex connections and Fast EtherChannel operation. The 10/100BASE-T interface module is available with 16K or 64K of memory. Routing tables use this memory.

10/100BASE-T Interface Module LEDs

Table 10-1 describes the LEDs used to confirm and troubleshoot the operation of interface modules. The LEDs on interface modules indicate the status of the modules and their ports.

100BASE-FX Interface Modules

The 100BASE-FX Ethernet interface module supports 100-Mbps Layer 2 or Layer 3 multimode fiber connections. This module supports full-duplex connections and Fast EtherChannel operation. It provides 16 multimode fiber ports that have MT-RJ connectors. The 100BASE-FX interface module is available with 16K or 64K of memory. Routing tables use this memory.

100BASE-FX Interface Module LEDs

Table 10-2 describes the LEDs used to confirm and troubleshoot the operation of interface modules. The LEDs on interface modules indicate the status of the modules and their ports.

Displaying 10/100BASE-T and 100BASE-FX Interface Module Configurations

To display the 10/100 Ethernet interface module configuration and status, use the following commands:

Follow these steps to troubleshoot a 10/100 Ethernet interface module: