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User's Manual of SGS-5240 Series Managed Switch
4.2.16 LLDP
Link Layer Discovery Protocol
Link Layer Discovery Protocol (LLDP) is used to discover basic information about neighboring devices on the local broadcast
domain. LLDP is a Layer 2 protocol that uses periodic broadcasts to advertise information about the sending device. Advertised
information is represented in Type Length Value (TLV) format according to the IEEE 802.1ab standard, and can include details
such as device identification, capabilities and configuration settings. LLDP also defines how to store and maintain information
gathered about the neighboring network nodes it discovers.
Link Layer Discovery Protocol - Media Endpoint Discovery (LLDP-MED) is an extension of LLDP intended for managing
endpoint devices such as Voice over IP phones and network switches. The LLDP-MED TLVs advertise information such as
network policy, power, inventory, and device location details. LLDP and LLDP-MED information can be used by SNMP
applications to simplify troubleshooting, enhance network management, and maintain an accurate network topology.
4.2.16.1 Global Configuration
Switch Management > LLDP > Global Configuration page is used to set attributes for general functions such as globally
enabling LLDP on the switch, setting the message ageout time, and setting the frequency for broadcasting general
advertisements or reports about changes in the LLDP MIB.
◆LLDP – Enables LLDP globally on the switch. (Default: Enabled)
◆Transmission Interval – Configures the periodic transmit interval for LLDP advertisements. (Range: 5-32768 seconds;
◆Hold Time Multiplier – Configures the time-to-live (TTL) value sent in LLDP advertisements as shown in the formula below.
Default: 30 seconds)
(Range: 2-10; Default: 4) The time-to-live tells the receiving LLDP agent how long to retain all information pertaining to the
sending LLDP agent if it does not transmit updates in a timely manner. TTL in seconds is based on the following rule: minimum
◆Delay Interval – Configures a delay between the successive transmission of advertisements initiated by a change in local
value ((Transmission Interval * Holdtime Multiplier), or 65535) Therefore, the default TTL is 4*30 = 120 seconds.
LLDP MIB variables. (Range: 1-8192 seconds; Default: 2 seconds) The transmit delay is used to prevent a series of successive
LLDP transmissions during a short period of rapid changes in local LLDP MIB objects, and to increase the probability that
multiple, rather than single changes, are reported in each transmission. This attribute must comply with the rule: (4 * Delay
Interval) δ Transmission Interval
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