Chapter 6 Troubleshooting

Diagnosing Problems

Note When ordering or using CX1 cables, ensure that the version identifier is 2 or higher.

•For long wave SFP+ modules, a mode conditioning patch might improve performance over maximum link distances with MMF connections.

Interface Settings

Verify that the port or interface is not disabled or powered off. If a port or interface is manually shut down on either side of the link, it does not come up until you reenable the interface. Use the show interfaces privileged EXEC command to see if the interface is error-disabled, disabled, or shut down on either side of the connection. If needed, reenable the interface.

Ping End Device

Ping 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

STP loops can cause serious performance issues that look like port or interface problems.

A unidirectional link can cause loops. It occurs when the traffic sent by the switch is received by the neighbor, but the traffic from the neighbor is not received by the switch. A broken cable, other cabling problems, or a port issue could cause this one-way communication.

You can enable UniDirectional Link Detection (UDLD) on the switch to help identify unidirectional link problems. For information about enabling UDLD on the switch, see the “Understanding UDLD” section in the software configuration guide on Cisco.com.

Switch Performance

Speed, Duplex, and Autonegotiation

Port statistics that show a large amount of alignment errors, frame check sequence (FCS), or late-collisions errors, might mean a speed or duplex mismatch.

A common issue occurs when duplex and speed settings are mismatched between two switches, between a switch and a router, or between the switch and a workstation or server. Mismatches can happen when manually setting the speed and duplex or from autonegotiation issues between the two devices.

To maximize switch performance and to ensure a link, follow one of these guidelines when changing the duplex or the speed settings:

•Let both ports autonegotiate both speed and duplex.

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

•If a remote device does not autonegotiate, use the same duplex settings on the two ports. The speed parameter adjusts itself even if the connected port does not autonegotiate.

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Cisco Systems WSC385024TS, C3850NM210G manual Switch Performance, Interface Settings, Ping End Device, Spanning Tree Loops
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C3850NM41G, C3850NM210G, WSC385024TS specifications

Cisco Systems is a global leader in networking and telecommunications hardware, and its Catalyst series of switches are widely recognized for their innovation, reliability, and performance. Among the numerous models available, the Cisco WSC385024TS, C3850NM41G, and C3850NM210G stand out for their advanced features and capabilities tailored to meet the needs of modern enterprises.

The Cisco WSC385024TS is a stackable switch that offers 24 ports, and it is built on Cisco's IOS XE software. It is designed for high-density environments, making it ideal for organizations that require robust connectivity and scalability. This model supports advanced Layer 2 and Layer 3 features and facilitates intelligent traffic management through Quality of Service (QoS). One of its standout features is the ability to stack up to nine switches together, enabling centralized management and increased fault tolerance. The WSC385024TS also integrates security features such as 802.1X authentication and access control lists, which are essential for maintaining a secure network infrastructure.

The C3850NM41G is a versatile switch that comes with 41 Gigabit Ethernet ports, making it suitable for environments that demand high-speed connectivity. This model supports Cisco's innovative StackWise-480 technology, which provides increased bandwidth and reliable inter-switch communication. Additionally, it features Power over Ethernet (PoE) capabilities, allowing it to deliver power to connected devices such as IP phones and wireless access points, thereby simplifying cabling and reducing the need for additional power sources. The C3850NM41G is also equipped with built-in automatic fault detection and recovery, enhancing the overall resilience of the network.

Lastly, the C3850NM210G model offers 210 Gbps of switching capacity, making it ideal for data-intensive applications. This switch combines performance with security, supporting various security protocols such as Virtual Routing and Forwarding (VRF) and Dynamic Host Configuration Protocol (DHCP) snooping to protect against malicious activity. With its modular design, the C3850NM210G allows for easy upgrades and expansions, facilitating adaptive network growth.

In summary, the Cisco WSC385024TS, C3850NM41G, and C3850NM210G switches provide advanced features, robust performance, and high scalability, making them ideal choices for businesses aiming to enhance their network infrastructure while supporting cutting-edge technologies. Whether for small businesses or large enterprises, these models exemplify Cisco's commitment to delivering high-quality networking solutions that adapt to the evolving demands of today's digital landscape.
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