Chapter 3 Troubleshooting

Diagnosing Problems

•Verify that you are using the correct cable type. See Appendix A, “Connector and Cable Specifications,” for more information.

•Check for loose connections. Sometimes a cable appears to be seated, but is not. 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 provides a way for Cisco to 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 known, good module. Verify that this module supports this platform. See the “SFP Modules” section on page 1-7for a list of supported SFP modules.

•Use the show interfaces privileged EXEC command to check the port or 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

An obvious but sometimes overlooked cause of port connectivity failure is 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 or 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, other cabling, 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.

Cisco ME 3400 Ethernet Access Switch Hardware Installation Guide

 

OL-7677-04

3-3

 

 

 

Page 50 Page 52
Page 51
Image 51
Cisco Systems ME 3400 manual SFP Module Port Issues, Port and Interface Settings, Ping the End Device, Spanning Tree Loops
Page 50 Page 52

ME 3400 specifications

Cisco Systems ME 3400 Series is a robust family of Ethernet access switches designed specifically for service provider environments. These switches are engineered to deliver excellent performance, reliability, and flexibility, making them ideal for deploying Layer 2 and Layer 3 services to residential and business customers.

One of the prominent features of the ME 3400 series is its support for advanced Ethernet technologies. It provides extensive support for both traditional and modern Ethernet services, including Carrier Ethernet. With features such as Ethernet Operations, Administration, and Maintenance (EOAM), the ME 3400 aids in managing network performance and troubleshooting issues effectively. This capability ensures that service providers can deliver high-quality services and maintain optimal network health.

The ME 3400 series includes various models that support a range of port configurations, enabling scalability and adaptability to different network needs. This includes support for both Fast Ethernet and Gigabit Ethernet interfaces. The switches can accommodate multiple speed configurations, making them versatile for diverse deployment scenarios, from small businesses to large enterprise networks.

Another key characteristic of the ME 3400 is its integrated support for resilient Ethernet technologies, such as EtherChannel, Spanning Tree Protocol (STP), and Rapid Spanning Tree Protocol (RSTP). These technologies enhance redundancy and improve network reliability, crucial for service providers who require minimal downtime and high service availability.

Security is a top priority for service providers, and the ME 3400 series addresses this with extensive security features. It supports VLANs for traffic segmentation, access control lists (ACLs) for traffic filtering, and DHCP snooping to prevent unauthorized access to the network. These security measures ensure that both consumer and enterprise traffic remains isolated and secure.

Additionally, the ME 3400 series supports IPv4 and IPv6 routing, offering flexibility for service providers to cater to a broad customer base. The ability to manage both protocols ensures that networks can evolve seamlessly as internet traffic transitions to IPv6.

With energy efficiency increasingly becoming a concern, Cisco has integrated power-saving features into the ME 3400 series. These switches support Energy Efficient Ethernet (EEE) technology, which reduces power consumption during periods of low traffic, helping service providers to reduce operational costs.

In summary, the Cisco ME 3400 series is a versatile platform rich in features that streamline service delivery while ensuring high performance, security, and energy efficiency. It is an ideal choice for service providers looking to enhance their Ethernet services and meet evolving customer demands.
Top Page Image Contents