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Configuration Guide - Network Management and Monitoring

S1720, S2700, S5700, and S6720 V200R011C10

This document provides the configurations of network management and monitoring features supported by the product, including SNMP, RMON and RMON2, LLDP, Performance Management, iPCA, NQA, Service Diagnosis, Mirroring, Packet Capture, NetStream, sFlow, TWAMP Light, and NETCONF.

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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
LLDP Frame Format

LLDP Frame Format

An LLDP frame is an Ethernet frame encapsulated with an LLDP data unit (LLDPDU). Figure 4-2 shows the LLDP frame format.

Figure 4-2  LLDP frame format

An LLDP frame contains the following fields:

  • DA: destination MAC address, a fixed multicast MAC address 0x0180-C200-000E
  • SA: source MAC address, the MAC address of the sender
  • Type: packet type, 0x88CC in LLDP frames
  • LLDPDU: LLDP data unit, body of an LLDP frame
  • FCS: frame check sequence.


An LLDPDU contains local device information and is encapsulated in an LLDP frame. Each LLDPDU consists of several information elements known as Type, Length, and Value (TLV) fields. The local device encapsulates its local information in TLVs, constructs an LLDPDU with several TLVs, and encapsulates the LLDPDU in the data field of an LLDP frame. Figure 4-3 shows the LLDPDU structure.

Figure 4-3  LLDPDU structure

As shown in Figure 4-3, an LLDPDU has four mandatory TLVs: Chassis ID TLV, Port ID TLV, Time to Live TLV, and End of LLDPDU TLV. Other TLVs are optional, and a device can determine whether to encapsulate them in an LLDPDU.

When LLDP is disabled on an interface or an interface is shut down, the interface sends a shutdown LLDPDU to the neighbors. In the shutdown LLDPDU, the value of the Time to Live TLV is 0. A shutdown LLDPDU contains no optional TLVs.

TLV Structure

An LLDPDU is formed by TLVs, and each TLV is an information element.

Figure 4-4 shows the structure of a TLV.

Figure 4-4  TLV structure

A TLV contains the following fields:

  • TLV Type (7 bits): type of a TLV. Each TLV type has a unique value. For example, the value of End of LLDPDU TLV is 0, and the value of Chassis ID TLV is 1.
  • TLV Length (9 bits): size of a TLV.
  • TLV Value (0-511 bytes): The first bit indicates the sub-type of a TLV, and the other bits are the TLV content.

TLV Type

LLDPDUs can encapsulate basic TLVs, TLVs defined by the IEEE 802.1 working groups, TLVs defined by IEEE 802.3 working groups, and Media Endpoint Discovery (MED) TLVs. Basic TLVs are used for basic device management. The TLVs defined by the IEEE 802.1 and IEEE 802.3 working groups, and MED TLVs defined by other organizations are used for enhanced device management functions. A device determines whether to encapsulate organizationally specific TLVs.

  • Basic TLVs

    Four basic TLVs are mandatory in LLDP implementation and must be encapsulated in an LLDPDU.
    Table 4-1  Basic TLVs




    Chassis ID TLV

    Bridge MAC address of the device sending an LLDPDU.


    Port ID TLV

    Name of the port from which an LLDPDU is sent.


    Time To Live TLV

    Time to live (TTL) of the local device information stored on the neighbor device.


    End of LLDPDU TLV

    End of an LLDPDU.


    Port Description TLV

    Character string that describes the port sending an LLDPDU.


    System Name TLV

    Device name.


    If the ip domain-name command has been executed to add a suffix to the device name, this TLV displays "device name.suffix".

    For example, if the device name is HUAWEI and suffix is area1, this TLV is HUAWEI.area1.


    System Description TLV

    Character string that describes the system.


    System Capabilities TLV

    Main functions of the system and the functions that have been enabled.


    Management Address TLV

    Address used by the NMS to identify and manage the local device. Management IP addresses uniquely identify network devices, facilitating layout of the network topology and network management.


  • TLVs defined by the IEEE 802.1 working group

    Table 4-2  TLVs defined by the IEEE 802.1 working group



    Port VLAN ID TLV

    VLAN ID of a port.

    Port And Protocol VLAN ID TLV

    Protocol VLAN ID of a port.

    VLAN Name TLV

    Name of the VLAN on a port.

    Protocol Identity TLV

    Protocol types that a port supports.

  • TLVs defined by the IEEE 802.3 working group

    Table 4-3  TLVs defined by the IEEE 802.3 working group




    Specifies whether a port supports Energy Efficient Ethernet (EEE).

    Link Aggregation TLV

    Specifies whether a port supports link aggregation and has link aggregation enabled.

    MAC/PHY Configuration/Status TLV

    Rate and duplex mode of a port, whether the port supports auto-negotiation, and whether auto-negotiation is enabled on the port.

    Maximum Frame Size TLV

    Maximum frame length that a port supports. The value is the maximum transmission unit (MTU) of the port.

    Power Via MDI TLV

    Power capabilities of a port, for example, whether a port supports PoE and whether a port supplies or demands power.

  • MED TLVs

    MED TLVs are related to voice over IP (VoIP) applications and provide functions such as basic configuration, network policy configuration, address management, and directory management. These TLVs meet the requirements of voice device manufacturers for cost efficiency, easy deployment, and easy management. Use of these TLVs allows the deployment of voice devices on Ethernet network. This brings great convenience for manufacturers, sellers, and users of voice devices.

    When the switch detects that the LLDP packet sent by an LLDP neighbor on an interface contains any type of MED TLV, the switch advertises all MED TLVs that can be advertised on the interface to the LLDP neighbor. However, the LLDP neighbor may support only parts of MED TLVs advertised by the switch, leading to an LLDP negotiation failure. You can run the undo lldp tlv-enable med-tlv command to enable the interface not to advertise the MED TLV that is not supported by the LLDP neighbor. For example, if a terminal does not support the 802.3af standard, that is, Extended Power-via-MDI TLV cannot be identified, run the undo lldp tlv-enable med-tlv power-over-ethernet command on the interface connected to the terminal to enable the interface not to advertise Extended Power-via-MDI TLV.

    Table 4-4  LLDP-MED TLVs



    LLDP-MED Capabilities TLV

    Type of a device and types of LLDP-MED TLVs that can be encapsulated in an LLDPDU.

    Inventory TLV

    Manufacturer of the device.

    Location Identification TLV

    Location of the local device.

    Network Policy TLV

    VLAN ID, Layer 2 priority, and DSCP of a voice VLAN.

    Extended Power-via-MDI TLV

    Power capability of the system.

    Hardware Revision TLV

    Hardware version of a media endpoint (ME).

    Firmware Revision TLV

    Firmware version of an ME device.

    Software Revision TLV

    Software version of an ME device.

    Serial Number TLV

    Serial number of an ME device.

    Model Name TLV

    Model name of an ME device.

    Asset ID TLV

    Asset identifier of an ME device.

Updated: 2020-02-06

Document ID: EDOC1000178174

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