1-11LLDP-CDP (CDP is short for the Cisco Discovery Protocol) packets use only SNAP encapsulation.Configuring CDP CompatibilityFor detailed information about voice VLAN, refer to VLAN Configuration in the Access Volume.You need to enable CDP compatibility for your device to work with Cisco IP phones.As your LLDP-enabled device cannot recognize CDP packets, it does not respond to the requests ofCisco IP phones for the voice VLAN ID configured on the device. This can cause a requesting Cisco IPphone to send voice traffic without any tag to your device, disabling your device to differentiate the voicetraffic from other types of traffic.By configuring CDP compatibility, you can enable LLDP on your device to receive and recognize CDPpackets from Cisco IP phones and respond with CDP packets carrying the voice VLAN configurationTLV for the IP phones to configure the voice VLAN automatically. Thus, the voice traffic is confined inthe configured voice VLAN to be 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.
