H3C LS-3100-52P-OVS-H3 Operation Manual - page 91
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To enable the neighboring devices to be informed of the existence of a device or an LLDP operating
mode change (from the disable mode to TxRx mode, or from the Rx mode to Tx mode) timely, a device
can invoke the fast sending mechanism. In this case, the interval to send LLDPDUs changes to one
second. After the device sends specific number of LLDPDUs, the interval restores to the normal. (A
neighbor is discovered when a device receives an LLDPDU and no information about the sender is
locally available.)
Receiving LLDPDUs
An LLDP-enabled device operating in TxRx mode or Rx mode checks the TLVs carried in the LLDPDUs
it receives and saves the valid neighboring information. An LLDPDU also carries a TTL (time to live)
setting with it. The information about a neighboring device maintained locally ages out when the
corresponding TTL expires.
The TTL of the information about a neighboring device is determined by the following expression:
TTL multiplier × LLDPDU sending interval
You can set the TTL by configuring the TTL multiplier. Note that the TTL can be up to 65535 seconds.
TTLs longer than it will be rounded off to 65535 seconds.
TLV Types
TLVs encapsulated in LLDPDUs fall into these categories: basic TLV, organization defined TLV, and
MED (media endpoint discovery) related TLV. Basic TLVs are the base of device management.
Organization specific TLVs and MED related TLVs are used for enhanced device management. They
are defined in standards or by organizations and are optional to LLDPDUs.
Basic LLDP TLVs
Table 1-1
lists the basic LLDP TLV types that are currently in use.
Table 1-1 Basic LLDP TLVs
Type
Description
Remarks
End of LLDPDU TLV
Marks the end of an LLDPDU.
Chassis ID TLV
Carries the bridge MAC address of the sender
Port ID TLV
Carries the sending port. For devices that do not
send MED TLVs, port ID TLVs carry sending port
name. For devices that send MED TLVs, port ID
TLVs carry the MAC addresses of the sending
ports or bridge MAC addresses (if the MAC
addresses of the sending ports are unavailable).
Time To Live TLV
Carries the TTL of device information
Required for
LLDP