Chapter 15 LLDP

Note:

Only TL-SG3424P supports LLDP function.

LLDP (Link Layer Discovery Protocol) is a Layer 2 protocol that is used for network devices to advertise their own device information periodically to neighbors on the same IEEE 802 local area network. The advertised information, including details such as device identification, capabilities and configuration settings, is represented in TLV (Type/Length/Value) format according to the IEEE 802.1ab standard, and these TLVs are encapsulated in LLDPDU (Link Layer Discovery Protocol Data Unit). The LLDPDU distributed via LLDP is stored by its recipients in a standard MIB (Management Information Base), making it possible for the information to be accessed by a Network Management System (NMS) using a management protocol such as the Simple Network Management Protocol (SNMP).

An IETF Standard MIB, as well as a number of vendor specific MIBs, have been created to describe a network's physical topology and associated systems within that topology. However, there is no standard protocol for populating these MIBs or communicating this information among stations on the IEEE 802 LAN. LLDP protocol specifies a set. The device running LLDP can automatically discover and learn about the neighbors, allowing for interoperability between the network devices of different vendors. This protocol allows two systems running different network layer protocols to learn about each other.

LLDP-MED (Link Layer Discovery Protocol for Media Endpoint Devices) is an extension of LLDP intended for managing endpoint devices such as Voice over IP phones and network switches. The LLDP-MED TLVs advertise information such as network policy, power via MDI, inventory management, and device location details.

The LLDP and LLDP-MED information can be used by SNMP applications to simplify troubleshooting, enhance network management, and maintain an accurate network topology.

LLDPDU Format

Each LLDPDU includes an ordered sequence of three mandatory TLVs followed by one or more optional TLVs plus an End of LLDPDU TLV, as shown in the figure below. Chassis ID TLV, Port ID TLV, TTL TLV and End TLV are the four mandatory TLVs for a LLDPDU. Optional TLVs provide various details about the LLDP agent advertising them and they are selected by network management.

The maximum length of the LLDPDU shall be the maximum information field length allowed by the particular transmission rate and protocol. In IEEE 802.3 MACs, for example, the maximum LLDPDU length is the maximum data field length for the basic, untagged MAC frame (1500 octets).

LLDP Working Mechanism

1)LLDP Admin Status

The transmission and the reception of LLDPDUs can be separately enabled for every port, making it possible to configure an implementation to restrict the port either to transmit only or receive only,

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TP-Link TL-SG3424P manual  Lldpdu Format
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TL-SG3424P specifications

The TP-Link TL-SG3424P is a high-performance managed switch designed to meet the needs of small to medium-sized businesses. Offering 24 Gigabit Ethernet ports, this device is an ideal solution for improving network efficiency and ensuring seamless data transfer across multiple devices. The switch not only facilitates connectivity but also provides robust management features to enhance the performance and security of your network.

One of the standout features of the TL-SG3424P is its Power over Ethernet (PoE) capability, which allows it to deliver power and data over the same Ethernet cable. This feature is particularly beneficial for deploying devices such as IP cameras, VoIP phones, and wireless access points without the need for additional power sources. With a total power budget of 250W, the TL-SG3424P can support a diverse range of PoE devices, providing convenience and flexibility in deployment.

In terms of management, the TL-SG3424P offers a user-friendly web interface, allowing network administrators to configure and monitor the switch with ease. It supports advanced Layer 2 features, including VLANs, Quality of Service (QoS), and Link Aggregation. These features enhance network performance by optimizing traffic flow and prioritizing essential applications. The switch also includes comprehensive security features, such as Port Security and Access Control Lists (ACL), which help protect against unauthorized access and ensure data integrity.

The build quality of the TL-SG3424P is robust, designed to handle demanding network environments. It includes a fanless design, which ensures silent operation, making it suitable for office environments where noise can be a distraction. The metal chassis is durable and built for longevity, ensuring that the device will withstand rigorous usage over time.

Furthermore, the TL-SG3424P supports SNMP (Simple Network Management Protocol), allowing for centralized network monitoring and management. This makes it easier for IT teams to keep track of network health and performance, enabling timely interventions when necessary.

In conclusion, the TP-Link TL-SG3424P is a versatile and powerful managed switch that combines PoE capabilities with advanced network management features, making it a perfect choice for businesses looking to upgrade their network infrastructure. With its reliable performance and robust features, it provides an excellent solution for enhancing productivity and connectivity in any office setting.
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