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The
CDP
neighbor-information command show the CDP neighboring device information that can be
recognized by the switch.
To make your device work with Cisco IP phones, you must enable CDP compatibility.
If 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. As a result, a requesting Cisco IP
phone sends voice traffic without any VLAN tag to your device. Your device cannot differentiate the
voice traffic from other types of traffic.
CDP compatibility enables your device to receive and recognize CDP packets from a Cisco IP phone
and respond with CDP packets carrying TLVs with the voice VLAN configuration. According to TLVs
with the voice VLAN configuration, the IP phone automatically configures the voice VLAN. As a result,
the voice traffic is confined in the configured voice VLAN and differentiated from other types of traffic.
For more information about voice VLANs, see "Configuring a voice VLAN."
Configuration prerequisites
Before you configure CDP compatibility, complete the following tasks:
•
Globally enable LLDP.
•
Enable LLDP on the port connecting to a device supporting CDP.
•
Configure the port to operate in TxRx mode.
Configuration procedure
CAUTION:
The maximum TTL value that CDP allows is 255 seconds. To make CDP-compatible LLDP work
correctly with Cisco IP phones, make sure the product of the TTL multiplier and the LLDP frame
transmission interval is less than 255 seconds.
CDP-compatible LLDP operates in one of the follows modes:
•
TxRx—CDP packets can be transmitted and received.
•
Disable—CDP packets cannot be transmitted or received.
To make CDP-compatible LLDP take effect on specific ports, follow these steps:
Enable CDP-compatible LLDP globally.
1.
Configure CDP-compatible LLDP to operate in TxRx mode on the port.
2.
To enable LLDP to be compatible with CDP:
Step
Enter system view.
1.
Enable CDP compatibility
2.
globally.
Enter Ethernet interface
3.
view or port group view.
neighbor-information-related
Command
system-view
lldp compliance cdp
•
•
fields
in
the
Enter Layer 2 Ethernet interface
view:
interface interface-type
interface-number
Enter port group view:
port-group manual
port-group-name
186
output
from
the
Remarks
N/A
Disabled by default.
N/A
display
lldp
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