Zte ZXR10 5900E Product Description page 54

ZXR10 5900E Product Description
To be simple, LLDP is a kind of neighbor discovery protocol. It defines criteria for network
devices in Ethernet such as switch, router and wireless LAN access points to enable
them to announce their existence to other nodes in the network and to store the
discovery information of each adjacent device. For example, the information of device
configuration and device identification can be declared by this protocol.
LLDP defines a universal announcement information set, a protocol that transmits the
announcement, and a method to store the received announcement information. The
device that announces its own information can put multiple announcements in one
LLDPDU (Link Layer Discovery Protocol Data Unit) to transmit them. The LLDPDU
contains a series of short message unit with variable length, which is called
type-length-value (TLV) with the description as follows:

Type indicates the type of the information needs to be sent

Length indicates the bytes of the information

Value indicates the actual information needs to be sent
Each LLDPDU contains four compulsory TLV and one optional TLV:

Device ID TLV

Port ID TLV

TTL TLV

Optional TLV

LLDPDU end TLV
Device ID and port ID are used to identify the sender
TTL TLV notifies the receiver of the reservation period of all the information. If no update
is received from the sender in this period, all related information will be dropped by the
receiver. IEEE has defined a suggested update frequency of one transmission per 30
seconds.
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