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ME60 V800R010C10SPC500 Feature Description - System Management 01

This is ME60 V800R010C10SPC500 Feature Description - System Management
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Basic Concepts

Basic Concepts

LAD Packet Formats

Link Automatic Discovery (LAD) packets have three different formats, depending on the link type.
  • When Ethernet interfaces are used on links, LAD packets are encapsulated into Ethernet frames. Figure 10-1 shows the LAD packet format on Ethernet interfaces.

    Figure 10-1 LAD packet format on Ethernet interfaces

    Table 10-1 describes the fields in an LAD packet on Ethernet interfaces.
    Table 10-1 Fields in an LAD packet on Ethernet interfaces

    Field

    Length

    Description

    DA

    6 bytes

    Destination MAC address, a broadcast MAC address fixed at 0xFF-FF-FF-FF-FF-FF

    SA

    6 bytes

    Source MAC address, an interface's MAC address or a device's bridge MAC address

    NOTE:
    Use the interface's MAC address if there is one; otherwise, use the device's bridge MAC address.

    Type

    2 bytes

    Packet type, fixed at 0x0000

    Flag

    20 bytes

    LAD packet identifier, fixed as Huawei Link Search

    Information

    20-44 bytes

    LAD data unit, main part of an LAD packet

    FCS

    4 bytes

    Frame check sequence

  • When Ethernet sub-interfaces are used on links, LAD packets are encapsulated into Ethernet frames. Figure 10-2 shows the LAD packet format on Ethernet sub-interfaces.

    Figure 10-2 LAD packet format on Ethernet sub-interfaces

    Table 10-2 describes the fields in an LAD packet on Ethernet sub-interfaces.
    Table 10-2 Fields in an LAD packet on Ethernet sub-interfaces

    Field

    Length

    Description

    DA

    6 bytes

    Destination MAC address, a broadcast MAC address fixed at 0xFF-FF-FF-FF-FF-FF

    SA

    6 bytes

    Source MAC address, an interface's MAC address or a device's bridge MAC address

    NOTE:
    Use the interface's MAC address if there is one; otherwise, use the device's bridge MAC address.

    Tag

    4 bytes

    2-byte Ethernet Type field and 2-byte VLAN field included

    Type

    2 bytes

    Packet type, fixed at 0x0806

    Field

    6 bytes

    Four fields included:
    • Hardware Type, fixed at 0xFF-FF
    • Protocol Type, fixed at 0xFF-FF
    • Hardware Length, fixed at 0x00
    • Protocol Length, fixed at 0x00

    Flag

    20 bytes

    LAD packet identifier, fixed as Huawei Link Search

    Information

    20-44 bytes

    LAD data unit, main part of an LAD packet

    FCS

    4 bytes

    Frame check sequence

  • When low-speed interfaces are used on links, LAD packets are encapsulated into PPP frames. Figure 10-3 shows the LAD packet format on low-speed interfaces.

    Figure 10-3 LAD packet format on low-speed interfaces

    Table 10-3 describes the fields in an LAD packet on low-speed interfaces.
    Table 10-3 Fields in an LAD packet on low-speed interfaces

    Field

    Length

    Description

    Flag1

    1 byte

    PPP frame's start ID, fixed at 0x7E

    Address

    1 byte

    Remote device's address, fixed at 0xFF

    Control

    1 byte

    PPP frame type, fixed at 0x03, indicating an unsequenced frame

    Protocol

    2 bytes

    Packet type (LAD) carried by PPP frames, fixed at 0xce05

    Flag2

    20 bytes

    LAD packet identifier, fixed as Huawei Link Search

    Information

    20-44 bytes

    LAD data unit, main part of an LAD packet

    FCS

    2 bytes

    Frame check sequence

    Flag3

    1 byte

    PPP frame's end ID, fixed at 0x7E

The Information field is the same in all the three LAD packet formats, meaning that the LAD data units are irrelevant to the link type. Figure 10-4 shows the format of the LAD data unit.
Figure 10-4 LAD data unit format

Table 10-4 describes the fields in the LAD data unit.
Table 10-4 LAD data unit fields

Field

Length

Description

Type

1 byte

LAD data unit type:
  • 1: Link Detect packet
  • 2: Link Reply packet

Version

1 byte

LAD protocol version, fixed at 1

Length

2 bytes

LAD data unit length

Value

12-16 bytes

LAD data unit's sub TLV:
  • Send Link Info SubTLV
  • Recv Link Info SubTLV

LAD Packet Types

LAD packets are classified as Link Detect or Link Reply packets, depending on the LAD data unit type.
  • Link Detect packets: link discovery requests triggered by the NMS or command lines. Link Detect packets carry Send Link Info SubTLV in the data unit. Figure 10-5 shows the format of the Link Detect packet data unit.

    Figure 10-5 Link Detect packet data unit format

  • Link Reply packets: link discovery replies in response to the Link Detect packets sent by remote devices. Link Reply packets carry the Send Link Info SubTLV (the same as that in the received Link Detect packets) and Recv Link Info SubTLV. Figure 10-6 shows the format of the Link Reply packet data unit.

    Figure 10-6 Link Reply packet data unit format

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Updated: 2019-01-04

Document ID: EDOC1100059466

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