Allied Telesis AT-FL-XS9X-UDLD UDLD LICS FOR XS900MX SERIES

Product Overview

The Allied Telesis AT-FL-XS9X-UDLD is a software license that enables Unidirectional Link Detection (UDLD) on compatible Allied Telesis x950 and x930 series switches. UDLD is a Layer 2 protocol that actively monitors fiber and copper links for unidirectional failures, preventing network loops and data loss that standard STP cannot detect. This single-license activation delivers an essential layer of resilience to enterprise and campus switching deployments.

Product Description

Unidirectional Link Detection (UDLD) monitors point-to-point fiber or copper links for physical faults that cause traffic to flow in only one direction — a failure mode that Spanning Tree Protocol alone cannot resolve. When UDLD detects a unidirectional condition, it shuts down the affected port immediately, eliminating potential network loops and black-holing of traffic. The AT-FL-XS9X-UDLD license unlocks this capability on Allied Telesis XS900MX series switches (including x950 and x930 platforms), integrating seamlessly with the AlliedWare Plus operating system. Activation is performed directly through the switch CLI or Allied Telesis Management Framework (AMF). A single license covers one switch and requires no subscription renewal. This is an essential add-on for network operators running high-availability fiber uplinks, ring topologies, or resilient campus cores where silent link failures are unacceptable.

Key Features

• UDLD Protocol Support — Detects and disables unidirectional fiber and copper links before they cause network loops or traffic black-holes.
• Compatible with XS900MX / x950 / x930 Series — Activates directly on Allied Telesis switches running AlliedWare Plus firmware.
• Per-Switch Licensing — One license covers one switch unit with no ongoing subscription fees.
• CLI & AMF Activation — Simple activation via AlliedWare Plus CLI or Allied Telesis Management Framework.
• Complements STP — Fills the detection gap left by Spanning Tree Protocol for unidirectional physical faults.
• Software Delivery — License key delivered electronically; no hardware required.

Technical Specifications

Frequently Asked Questions

Q: Which switches does the AT-FL-XS9X-UDLD license support?

It is compatible with Allied Telesis XS900MX series switches, including the x950 and x930 product families running AlliedWare Plus firmware.

Q: Is this a subscription license?

No. The AT-FL-XS9X-UDLD is a perpetual per-switch license with no recurring fees.

Q: Why is UDLD needed if STP is already enabled?

Spanning Tree Protocol detects logical loops but cannot identify a unidirectional physical link failure on its own. UDLD actively sends keep-alive messages and shuts down any port where traffic flows in only one direction, preventing silent failures.

Q: How is the license activated?

The license key is entered via the AlliedWare Plus CLI using the license install command, or through the Allied Telesis Management Framework (AMF).

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