User manual

LLDP (Link Layer Discovery Protocol)
6874_en_09 PHOENIX CONTACT 9-1
9 LLDP (Link Layer Discovery Protocol)
9.1 Basics
LLDP The switch supports LLDP according to IEEE 802.1ab and enables topology detection of
devices that also have LLDP activated.
Advantages of using LLDP:
– Improved error location detection.
– Improved device replacement.
– More efficient network configuration.
The following information is received by neighbors or sent to neighbors, as long as LLDP
is activated:
– The device sends its own management and connection information to neighboring
devices.
– The device receives management and connection information from neighboring
devices.
Displaying LLDP
information
The information that is collected is presented in a table in WBM. The table includes port
numbers that are used to connect both devices together, as well as the IP address, the
device name of neighboring devices, and the device type.
LLDP general The Link Layer Discovery Protocol (LLDP) according to 802.1ab is used by network
devices to learn and maintain the individual neighbor relationships.
Function
A network infrastructure component transmits a port-specific BPDU (Bridge Protocol Data
Unit) at the "Message Transmit Interval", which contains the individual device information,
to each port in order to distribute topology information. The partner connected to the
relevant port learns the corresponding port-specific neighbors from these BPDUs.
The information learned from the BPDUs is saved for a defined period of time as the TTL
value (TTL - Time To Live). Subsequent receipt of the same BPDUs increases the TTL
value again and the information is still saved. If the TTL elapses, the neighbor information
is deleted.
An MMS manages a maximum of 50 items of neighbor information, all other information
is ignored.
If several neighbors are displayed on one switch port, then there must be at least
another switch/hub installed between this switch and the neighbor indicated, which
LLDP does not support or has not activated.