1-11With CDP compatibility enabled, the device can use LLDP to receive and recognize CDP packets fromCisco IP phones and respond with CDP packets carrying the voice VLAN ID of the device for the IPphones to configure the voice VLAN automatically. In this way, voice traffic is confined in the configuredvoice VLAN and is thus differentiated from other types of traffic.Configuration PrerequisitesBefore configuring CDP compatibility, make sure that:z LLDP is enabled globally.z LLDP is enabled on the port connected to an IP phone and is configured to operate in TxRx modeon the port.Configuring CDP CompatibilityCDP-compatible LLDP operates in one of the follows two modes:z TxRx, where CDP packets can be transmitted and received.z Disable, where CDP packets can neither be transmitted nor be received.To make CDP-compatible LLDP take effect on certain ports, first enable CDP-compatible LLDP globallyand configure CDP-compatible LLDP to operate in TxRx mode.Follow these steps to enable LLDP to be compatible with CDP:To do… Use the command… RemarksEnter system view system-view —Enable CDP compatibilityglobally lldp compliance cdp RequiredDisabled by default.Enter Ethernet interface view interface interface-typeinterface-number RequiredConfigure CDP-compatibleLLDP to operate in TxRxmodelldp compliance admin-status cdptxrxRequiredBy default,CDP-compatible LLDPoperates in disable mode.As the maximum TTL allowed by CDP is 255 seconds, ensure that the product of the TTL multiplier andthe LLDPDU transmit interval is less than 255 seconds for CDP-compatible LLDP to work properly withCisco IP phones. You can use related commands to configure the TTL multiplier and the LLDPDUtransmit interval. For details, see Setting Other LLDP Parameters.Configuring LLDP TrappingLLDP trapping is used to notify the network management system (NMS) of events such as newneighboring devices detected and link malfunctions.To prevent excessive LLDP traps from being sent when topology is unstable, you can set a minimumtrap sending interval for LLDP.
