Udld Overview - Cisco 300 Series Administration Manual

Managed switch

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Table of Contents

Port Management: Unidirectional Link

UDLD Overview

Cisco Small Business 200, 300 and 500 Series Managed Switch Administration Guide (Internal Version)

This section describes how the Unidirectional Link Detection (UDLD) feature.

It covers the following topics:

UDLD Overview

UDLD Operation

Usage Guidelines

Dependencies On Other Features

Default Settings and Configuration

Before You Start

Common UDLD Tasks

Configuring UDLD

UDLD is a Layer 2-protocol that enables devices connected through fiber-optic or

twisted-pair Ethernet cables to detect unidirectional links. A unidirectional link

occurs whenever traffic from a neighboring device is received by the local device,

but traffic from the local device is not received by the neighbor.

The purpose of UDLD is to detect ports on which the neighbor does not receive

traffic from the local device (unidirectional link) and to shut down those ports.