H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 144)

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• Disable mode. A port in this mode does not send or receive LLDPDUs.
When the LLDP operating mode of a port changes, its LLDP protocol state machine re-initializes. A
re-initialization delay, which is user configurable, prevents LLDP from being initialized too frequently
during times of frequent operating mode change. With this delay configured, before a port can initialize
LLDP, it must wait for the specified interval after the LLDP operating mode changes.
Transmitting LLDPDUs
An LLDP-enabled port operating in TxRx mode or Tx mode sends LLDPDUs to its directly connected
devices both periodically and when the local configuration changes. A frame transmit interval between
two successive LLDP frames prevents the network from being overwhelmed by LLDPDUs during times of
frequent local device information change.
This interval is shortened to 1 second in either of the following cases:
• A new neighbor is discovered. A new LLDPDU is received carrying device information new to the
local device.
• The LLDP operating mode of the port changes from Disable/Rx to TxRx or Tx.
This is the fast sending mechanism of LLDP. This feature sends a specific number of LLDPDUs at 1-second
intervals to help LLDP neighbors discover the local device as soon as possible. Then, the normal LLDPDU
transmit interval resumes.
Receiving LLDPDUs
An LLDP-enabled port operating in TxRx mode or Rx mode checks the validity of TLVs carried in every
received LLDPDU. If valid, the information is saved and an aging timer is set for it based on the time to
live (TTL) value in the Time to Live TLV carried in the LLDPDU. If the TTL value is zero, the information is
aged out immediately.
Protocols and standards
• IEEE 802.1AB-2005, Station and Media Access Control Connectivity Discovery
• ANSI/TIA-1057, Link Layer Discovery Protocol for Media Endpoint Devices
LLDP configuration task list
Complete these tasks to configure LLDP:
Task Remarks
Performing basic LLDP
configuration
Enabling LLDP Required
Setting the LLDP operating mode Optional
Setting the LLDP re-initialization delay Optional
Enabling LLDP polling Optional
Configuring the advertisable TLVs Optional
Configuring the management address and its
encoding format
Optional
Setting other LLDP parameters Optional
Setting an encapsulation format for LLDPDUs Optional