H3C S5500-SI Series, Operation Manual

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LLDP-CDP (CDP is short for the Cisco Discovery Protocol) packets use only SNAP encapsulation.
Configuring CDP Compatibility
For 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 of
Cisco IP phones for the voice VLAN ID configured on the device. This can cause a requesting Cisco IP
phone to send voice traffic without any tag to your device, disabling your device to differentiate the voice
traffic from other types of traffic.
By configuring CDP compatibility, you can enable LLDP on your device to receive and recognize CDP
packets from Cisco IP phones and respond with CDP packets carrying the voice VLAN configuration
TLV for the IP phones to configure the voice VLAN automatically. Thus, the voice traffic is confined in
the configured voice VLAN to be differentiated from other types of traffic.
Configuration Prerequisites
Before 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 mode
on the port.
Configuring CDP Compatibility
CDP-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 globally
and 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… Remarks
Enter system view system-view —
Enable CDP compatibility
globally
lldp compliance cdp
Required
Disabled by default.