Contents

• Troubleshooting the Cisco ME 2600X Shelf
• Check Switch Connections
• Check Switch Performance
• Environmental Alarms for Cisco ME 2600X

Troubleshooting the Cisco ME 2600X Shelf

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• Check Switch Connections
• Check Switch Performance
• Environmental Alarms for Cisco ME 2600X

Contents

• Troubleshooting the Cisco ME 2600X Shelf
• Check Switch Connections
• Check Switch Performance
• Environmental Alarms for Cisco ME 2600X

Troubleshooting the Cisco ME 2600X Shelf

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This chapter explains how to troubleshoot the Cisco ME 2600X shelf.

• Check Switch Connections
• Check Switch Performance
• Environmental Alarms for Cisco ME 2600X

Check Switch Connections

Review this section when troubleshooting switch connectivity problems.

Bad or Damaged Cable

Always check the cable for marginal damage or failure. A cable might be sufficient to connect at the physical layer but it could cause packet corruption because of subtle damage to its wiring or connectors. You can identify this situation by packet errors, or the port constantly loses and regains link. In these situations:

• Check or change the copper or fiber-optic cable with a good working cable.

• Look for broken or missing pins on cable connectors.

• Rule out any insufficient patch panel connections or media convertors between the source and the destination. If possible, bypass the patch panel or eliminate faulty media convertors, such as fiber-optic-to-copper convertors.

• Try using the cable in another port or interface to see if the problem exists there.

Ethernet and Fiber Cables

Make sure that you have the correct cable type for the connection:

• For Ethernet, use Category 3 copper cable for 10 Mb/s unshielded twisted pair (UTP) connections. Use either Category 5, Category 5e, or Category 6 UTP for 10/100 or 10/100/1000 Mb/s connections.

• For fiber-optic connectors, verify that you have the correct cable for the distance and port type. Make sure that the ports on the connected device match and that they use the same type of encoding, optical frequency, and fiber type.

• For copper connections, determine if a crossover cable was used when a straight-through cable was required, or the reverse. Enable auto-MDIX on the switch, or replace the cable.

Link Status

Verify that both sides are linked. A single broken wire or one shutdown port can cause one side to show link, but the other side does not have link.

A link LED does not guarantee that the cable is fully functional. The cable might have encountered physical stress that causes it to function at a marginal level. If the link light for the port does not come on:

• Connect the cable from the switch to a good working device.

• Make sure that both ends of the cable are connected to the correct ports.

• Verify that both devices have power.

• Verify that you are using the correct cable type.

• Check for loose connections. Sometimes a cable appears to be connected, but it might not be. Disconnect and then reconnect the cable.

SFP Module Port Issues

Use only Cisco small form-factor pluggable (SFP) modules on the switch. Each Cisco module has an internal serial EEPROM that is encoded with security information. This encoding helps us identify and validate that the module meets the requirements for the switch. Check these items:

• Bad or wrong SFP module. Exchange the suspect module with a good working module. Verify that this module supports this platform.

• Use the show interfaces privileged EXEC command to check the port for module error-disabled, disabled, or shutdown status. Re-enable the port if necessary.

• Make sure that all fiber-optic connections are properly cleaned and securely connected.

Port and Interface Settings

One of the causes for port connectivity failure could be a disabled port. Verify that the port or interface is not disabled or for some reason powered down. If a port or interface is manually shut down on one or the other side of the link, the link does not come up until you re-enable the port. Use the show interfaces privileged EXEC command to check the port for interface error-disabled, disabled, or shutdown status on both sides of the connection. If necessary, re-enable the port or the interface.

Ping the End Device

Check the end device by pinging it from the directly connected switch first, and then work your way back port by port, interface by interface, trunk by trunk, until you find the source of the connectivity issue. Make sure that each switch can identify the end device MAC address in its Content-Addressable Memory (CAM) table.

Spanning Tree Loops

Spanning Tree Protocol (STP) loops can cause serious performance issues that might appear to be port or interface problems. In this situation, the switch bandwidth is used repeatedly by the same frames, crowding out legitimate traffic.

A unidirectional link can cause loops. This occurs when the traffic that the switch sends is received by its neighbor, but the switch does not receive the traffic that is sent from the neighbor. A broken fiber-optic cable or a port issue could cause this one-way communication.

You can enable the UniDirectional Link Detection (UDLD) protocol on the switch to help identify difficult-to-find unidirectional link problems. UDLD supports a normal mode of operation (the default) and an aggressive mode. In normal mode, UDLD detects unidirectional links because of incorrectly connected interfaces on fiber-optic connections. In aggressive mode, UDLD also detects unidirectional links caused by one-way traffic on fiber-optic and twisted-pair links and by incorrectly connected interfaces on fiber-optic links. For information about enabling UDLD on the switch, see the "Understanding UDLD" section in the software configuration guide.

Check Switch Performance

Review this section when you troubleshoot switch performance problems.

Speed, Duplex, and Autonegotiation

If the port statistics show a large number of alignment errors, frame check sequence (FCS), or late-collisions errors, a speed or duplex mismatch might be the problem.

A common issue with speed and duplex occurs when the duplex settings are mismatched between two switches, between a switch and a router, or between the switch and a workstation or server. This can happen when you manually set the speed and duplex or because of autonegotiation issues between the two devices.

These circumstances can result in a mismatch:

• A manually set speed or duplex parameter is different from the manually set speed or duplex parameter on the connected port.

• A port is set to autonegotiate, and the connected port is set to full duplex with no autonegotiation.

To maximize switch performance and ensure a link, follow one of these guidelines when you set or change the settings for duplex and speed:

• Let both ports autonegotiate both speed and duplex.

• Manually set the speed and duplex parameters for the ports on both ends of the connection.

• If a remote device does not autonegotiate, configure the duplex settings on the two ports to match. The speed parameter can adjust itself even if the connected port does not autonegotiate.

Autonegotiation and NIC Cards

Problems sometimes occur between the switch and third-party network interface cards (NICs). By default, the switch ports and interfaces are set to autonegotiate. It is common for devices such as laptop computers or other devices to also be set to autonegotiate, yet sometimes autonegotation issues occur.

To troubleshoot autonegotiation problems, try manually setting both sides of the connection. If this does not solve the problem, the firmware or software on your NIC card might be causing the problem. Upgrade the NIC card driver to the latest version available from the manufacturer.

Cabling Distance

If the port statistics show excessive FCS, late-collision, or alignment errors, verify that the cable distance from the switch to the connected device meets the recommended guidelines.

Environmental Alarms for Cisco ME 2600X

The following environmental alarm report displays the alarm status and operating statistics for the switch power supplies and cooling fans.

Power Source	Component	Alarm Type	LED Indication	Action
DC	Switch temperature sensor exceeds 78 C	Critical	Light CRITICAL STATUS LED	Generates a syslog message.
DC	Switch temperature sensor exceeds 82 C	Critical	—	Resets the switch.
AC	Switch temperature sensor exceeds 55 C	Critical	Light CRITICAL STATUS LED	Generates a syslog message.
AC	Switch temperature sensor exceeds 60 C	Critical	—	Resets the switch.
AC or DC	Switch temperature sensor less than 0 C	No alarm	FAN STATUS LED green	Shuts down the fans.
AC or DC	One or more fan broken	Major	FAN STATUS LED red	Sets all the other fans to maximum speed. Generates a syslog message.
DC	One of the DC power source is out of range	Major	FAN STATUS LED red	Reports the alarm to the console.