Configuring Cdp Compatibility; Configuration Prerequisites - 3Com S7906E Configuration Manual

To do...
Enter system view
Enter Ethernet
interface view
or port group
view
Set the encapsulation format
for LLDPDUs to SNAP
Both the LLDPDU transmit interval and delay must be less than the TTL to ensure that the LLDP
neighbors can receive LLDP frames to update information about the device you are configuring before
it is aged out.

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:
LLDP is enabled globally.
LLDP is enabled on the port connected to an IP phone and is configured to operate in TxRx mode
on the port.
Use the command...
system-view
Enter
interface interface-type
Ethernet
interface-number
interface view
Enter port port-group manual
group view port-group-name
lldp encapsulation snap
1-11
Remarks
—
Required
Use either command.
Required
Ethernet II encapsulation
format applies by default.
To restore the default, use
the undo lldp
encapsulation command.