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Configuration Guide - Network Management and Monitoring

CloudEngine 12800 and 12800E V200R005C10

This document describes the configurations of Network Management and Monitoring, including SNMP, RMON, LLDP, NQA, Service Diagnosis, Mirroring, Packet Capture, sFlow, and NETCONF.
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LLDP Frame Format

LLDP Frame Format

An LLDP frame is an Ethernet frame encapsulated with an LLDP data unit (LLDPDU). Figure 6-2 shows the LLDP frame format.

Figure 6-2 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.

LLDPDU

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 6-3 shows the LLDPDU structure.

Figure 6-3 LLDPDU structure

As shown in Figure 6-3, 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 6-4 shows the structure of a TLV.

Figure 6-4 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 6-1 Basic TLVs

    TLV

    Description

    Mandatory

    Chassis ID TLV

    Bridge MAC address of the device sending an LLDPDU.

    Yes

    Port ID TLV

    Port from which an LLDPDU is sent.
    • If an LLDPDU does not contain any MED TLVs, the Port ID TLV identifies the port name.
    • If an LLDPDU contains a MED TLV, the Port ID TLV identifies the port MAC address. If the port has no MAC address, the Port ID TLV identifies the bridge MAC address.

    Yes

    Time To Live TLV

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

    Yes

    End of LLDPDU TLV

    End of an LLDPDU.

    Yes

    Port Description TLV

    Character string that describes the port sending an LLDPDU.

    No

    System Name TLV

    System name.

    No

    System Description TLV

    Character string that describes the system.

    No

    System Capabilities TLV

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

    No

    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.

    No

  • TLVs defined by the IEEE 802.1 working group

    Table 6-2 TLVs defined by the IEEE 802.1 working group

    TLV

    Description

    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 6-3 TLVs defined by the IEEE 802.3 working group

    TLV

    Description

    EEE TLV

    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.

  • DCBX TLV

    Data center bridging (DCB) information. Neighboring nodes on data center networks use the Data Center Bridging Exchange (DCBX) protocol to exchange and negotiate DCB information so that they have the same DCB information. This prevents packet loss on the data center network. DCBX encapsulates DCB information in DCBX TLVs and uses LLDP frames to exchange DCB information between neighboring nodes.

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Updated: 2019-04-20

Document ID: EDOC1100075344

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