Configuring Layer 2 Interfaces

About the Error-Disabled State

CDP runs on all media that support Subnetwork Access Protocol (SNAP). Because CDP runs over the data-link layer only, two systems that support different network-layer protocols can learn about each other.

Each CDP-configured device sends periodic messages to a multicast address, advertising at least one address at which it can receive SNMP messages. The advertisements also contain time-to-live, or holdtime information, which is the length of time a receiving device holds CDP information before discarding it. Each device also listens to the messages sent by other devices to learn about neighboring devices.

The switch supports both CDP Version 1 and Version 2.

Default CDP Configuration

The following table shows the default CDP configuration.

Table 3: Default CDP Configuration

 

Feature

Default Setting

CDP interface state

Enabled

CDP timer (packet update frequency)

60 seconds

CDP holdtime (before discarding)

180 seconds

CDP Version-2 advertisements

Enabled

About the Error-Disabled State

An interface is in the error-disabled (err-disabled) state when the inteface is enabled administratively (using the no shutdown command) but disabled at runtime by any process. For example, if UDLD detects a unidirectional link, the interface is shut down at runtime. However, because the interface is administratively enabled, the interface status displays as err-disabled. Once an interface goes into the err-disabled state, you must manually reenable it or you can configure an automatic timeout recovery value. The err-disabled detection is enabled by default for all causes. The automatic recovery is not configured by default.

When an interface is in the err-disabled state, use the errdisable detect cause command to find information about the error.

You can configure the automatic err-disabled recovery timeout for a particular err-disabled cause by changing the time variable.

The errdisable recovery cause command provides automatic recovery after 300 seconds. To change the recovery period, use the errdisable recovery interval command to specify the timeout period. You can specify 30 to 65535 seconds.

If you do not enable the err-disabled recovery for the cause, the interface stays in the err-disabled state until you enter the shutdown and no shutdown commands. If the recovery is enabled for a cause, the interface is brought out of the err-disabled state and allowed to retry operation once all the causes have timed out. Use the show interface status err-disabledcommand to display the reason behind the error.

Cisco Nexus 5000 Series NX-OS Interfaces Configuration Guide, Release 5.2(1)N1(1)

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Cisco Systems N5KC5596TFA manual About the Error-Disabled State, Default CDP Configuration

N5KC5596TFA specifications

The Cisco Systems N5KC5596TFA is a high-performance data center switch designed specifically for modern architectures requiring low-latency, high-bandwidth connectivity. As part of the Nexus 5000 series, the N5KC5596TFA addresses the needs of virtualized environments, cloud computing, and highly dynamic workloads, making it an essential choice for enterprises and service providers.

One of the standout features of the N5KC5596TFA is its impressive port density. The switch offers 48 10 Gigabit Ethernet (10GbE) ports and 4 40 Gigabit Ethernet (40GbE) uplinks, providing flexibility to connect a variety of devices and ensuring high throughput across the network. This port configuration is ideal for connecting multiple servers and storage devices, making it perfect for environments with significant data traffic.

The switch supports a range of advanced technologies such as Virtual Extensible LAN (VXLAN) for improving scalability and multi-tenancy in data center networks. VXLAN encapsulates Layer 2 Ethernet frames within Layer 4 UDP packets, allowing for a larger address space and effective overlay networking, which is crucial for cloud deployments.

Another notable aspect of the N5KC5596TFA is its support for Data Center Bridging (DCB), which enhances the reliability and performance of Ethernet networks. DCB features like Priority Flow Control (PFC) and Enhanced Transmission Selection (ETS) help to minimize data loss and ensure Quality of Service (QoS) for various types of traffic, including storage and regular data, which is critical in a converged infrastructure.

Security is also a priority with the N5KC5596TFA, as it comes equipped with features such as Access Control Lists (ACLs) and port security, helping to safeguard the network from unauthorized access and potential threats.

In terms of management, the switch offers integration with Cisco's Data Center Network Manager (DCNM), providing tools for monitoring, management, and automation, which simplifies operational tasks. Additionally, it supports Cisco's Application Centric Infrastructure (ACI), enabling a more comprehensive and application-focused approach to networking.

Overall, the Cisco Systems N5KC5596TFA is engineered for organizations looking to build robust, highly efficient, and secure data center environments. Its combination of high density, versatile connectivity options, and advanced networking technologies makes it a powerful solution for meeting the demands of today’s enterprise workloads.