R21xx-HP FlexFabric 11900 Layer 2 LAN Switching Configuration Guide

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Management address
The network management system uses the management address of a device to identify and manage the
device for topology maintenance and network management. The management address is encapsulated
in the management address TLV.
Work mechanism
LLDP operating modes
LLDP can operate in one of the following modes:
• TxRx mode—A port in this mode can send and receive LLDPDUs.
• Tx mode—A port in this mode can only send LLDPDUs.
• Rx mode—A port in this mode can only receive LLDPDUs.
• Disable mode—A port in this mode cannot send or receive LLDPDUs.
Each time the LLDP operating mode of a port changes, its LLDP protocol state machine re-initializes. A
configurable re-initialization delay prevents frequent initializations because of frequent changes to the
operating mode. 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. To prevent LLDPDUs from
overwhelming the network during times of frequent changes to local device information, you can set a
delay between two successive LLDPDUs.
This interval is shortened to 1 second in either of the following cases:
• A new neighbor is discovered. A new LLDPDU is received and carries device information new to the
local device.
• The LLDP operating mode of the port changes from Disable or Rx to TxRx or Tx.
This is the fast sending mechanism of LLDP. With this mechanism, a specific number of LLDPDUs are sent
successively 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 that is 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 TTL
value in the TTL TLV carried in the LLDPDU. If the TTL value is zero, the information ages 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
• DCB Capability Exchange Protocol Specification Rev 1.00
• DCB Capability Exchange Protocol Base Specification Rev 1.01
LLDP configuration task list