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Management address

The management address of a device is used by the network management system to identify and

manage the device for topology maintenance and network management. The management address is

encapsulated in the management address TLV.

How LLDP works

Operating modes of LLDP

LLDP can operate in one of the following modes:

 TxRx mode. A port in this mode sends and receives LLDPDUs.

 Tx mode. A port in this mode only sends LLDPDUs.

 Rx mode. A port in this mode only receives LLDPDUs.

 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

transit 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 TTL TLV carried in the LLDPDU. If the TTL value is zero, the information is aged out

immediately.

Compatibility of LLDP with CDP

To make your device work with Cisco IP phones, you must enable CDP compatibility.

If your LLDP-enabled device cannot recognize Cisco Discovery Protocol (CDP) packets, it does not

respond to the requests of Cisco IP phones for the voice VLAN ID configured on the device. As a result,

a requesting Cisco IP phone sends voice traffic without any tag to your device, disabling your device from

differentiating the voice traffic from other types of traffic.

HP V1910 Switch Series User Manual

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