Configuring Cdp Compatibility - 3Com 5500-EI PWR Install Manual

With SNAP encapsulation configured, an LLDP port sends LLDPDUs in SNAP frames and
processes only SNAP encapsulated incoming LLDPDUs.
By default, LLDPDUs are encapsulated in Ethernet II frames. If the neighbor devices encapsulate
LLDPDUs in SNAP frames, you can configure the encapsulation format for LLDPDUs as SNAP on the
port connected to the neighbor device, thus guaranteeing communication with the other devices in the
network.
Follow these steps to configure the encapsulation format for LLDPDUs:
To do...
Enter system view
Enter Ethernet interface view
Configure the encapsulation
format for LLDPDUs as SNAP
The configuration does not apply to LLDP-CDP packets, which use only SNAP encapsulation.

Configuring CDP Compatibility

For detailed information about voice VLAN, refer to Voice VLAN Operation in this manual.
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.
CDP-compatible LLDP operates in one of the follows two modes:
TxRx where CDP packets can be transmitted and received.
Disable where CDP packets can neither be transmitted nor be received.
Use the command...
system-view
interface interface-type
interface-number
lldp encapsulation snap
1-8
Remarks
—
Required
Required, the
configuration applies to
the current port only.
Ethernet II
encapsulation format
applies by default.