7 Link Layer Discovery Protocol (LLDP and LLDP-MED)
LLDP is a standardized discovery protocol defined by IEEE 802.1AB. It allows stations residing on a
LAN to advertise major capabilities, physical descriptions, and management information to other devices on the network. A network management system (NMS) can access and display this information.
LLDP is a one-way protocol; there are no request/response sequences. Information is advertised in
LLDP Protocol Data Units (LLDPDUs) by stations implementing the LLDP transmit function, and LLDP-
DUs are received and processed by stations implementing the receive function. The transmit and receive functions can be enabled and disabled separately per port. By default, both functions are enabled on all ports.
LLDP-MED is an extension of the LLDP standard. LLDP-MED uses LLDP's organizationally-specific
Type- Length-Value (TLV) extensions and defines additional TLVs.
LLDP Global Configuration
Use the LLDP Global Configuration page to specify global LLDP parameters and to configure the protocol on individual ports.
To display the LLDP Global Configuration page, click LLDP > Configuration in the navigation pane.
Figure 60. LLDP Global Configuration Page
LLDP Global Configuration 89
You can configure the following global settings:
Table 41. LLDP Global Configuration Fields
Field
Transmit Interval
Transmit Hold Multiplier
Re-Initialization Delay
Notification Interval
Description
Specify the time between transmission of LLDPDUs. The range is from 5 to 32768 seconds and the default is 30 seconds.
Specify the multiplier value on the transmit interval, which is used to compute the time-to-live
(TTL) value associated with LLDPDUs. The range is from 2 to 10 seconds, and the default is
4 seconds.
Specify the number of seconds to wait before attempting to re-initialize LLDP on a port after the LLDP operating mode on the port changes. The range is from 1 to 10 seconds and the default is 2 seconds.
Specify the minimum number of seconds to wait between transmissions of remote data change notifications. The range is from 5 to 3600 seconds and the default is 5 seconds.
If you change these settings, click Apply to save any changes for the current boot session. The changes take effect immediately but are not retained across a switch reset unless you click Save Con-
figuration.
The following information displays for each interface:
Table 42. LLDP Global Configuration—Port Fields
Field
Interface
Link Status
Transmit
Receive
Notify
Transmit Management
Information
Description
The port or trunk ID.
The link status of the interface, which is either Up or Down. An interface that is down does not forward traffic.
The LLDP advertise (transmit) mode on the interface. If the transmit mode is enabled, the interface sends LLDPDUs that advertise the mandatory TLVs that are enabled.
The LLDP receive mode on the interface. If the receive mode is enabled, the device can receive LLDPDUs from other devices.
Enable to have LLDP generate a log file entry.
The status of the LLDP remote data change notification on the interface. When enabled, the interface sends notifications when a link partner device is added or removed.
To modify interface settings, select one or more interfaces and click Edit to display the Edit LLDP Interface page.
Page 90 LLDP Global Configuration
