Compatibility Of Lldp With Cdp; Protocols And Standards; Configuring Lldp; Lldp Configuration Task List - 3Com Baseline 2928 PWR Plus User Manual

This is the fast sending mechanism of LLDP. With this mechanism, a specific number of LLDPDUs are
sent successively at the 1-second interval to help LLDP neighbors discover the local device as soon as
possible. Then, the normal LLDPDU transit interval resumes.
Receiving LLDPDUs
An LLDP-enabled port operating in TxRx mode or Rx mode checks the TLVs carried in every LLDPDU
it receives for validity violation. If valid, the information is saved and an aging timer is set for it based on
the time to live (TTL) TLV carried in the LLDPDU. If the TTL TLV is zero, the information is aged out
immediately.

Compatibility of LLDP with CDP

You need to enable CDP compatibility for your device to work with Cisco IP phones.
As your LLDP-enabled device cannot recognize Cisco Discovery Protocol (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 untagged to your device, disabling your device
to differentiate 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.

Protocols and Standards

The protocols and standards related to LLDP include:
IEEE 802.1AB-2005, Station and Media Access Control Connectivity Discovery
ANSI/TIA-1057, Link Layer Discovery Protocol for Media Endpoint Devices

Configuring LLDP

LLDP Configuration Task List

Perform the tasks in
Table 1-7 LLDP configuration task list
Task
Enabling LLDP on Ports
Table 1-1 to configure LLDP:
Optional
By default, LLDP is enabled on ports.
Make sure that LLDP is also enabled globally, because LLDP can work
on a port only when it is enabled both globally and on the port.
Remarks
1-6