A 4 Lldp - Link Layer Discovery Protocol - Phoenix Contact SCX 4POE 2LX User Manual

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A 4 LLDP – Link Layer Discovery Protocol
The Link Layer Discovery Protocol is used by network participants to learn and maintain the
individual neighbor relationships. The switch supports LLDP in accordance with
IEEE 802.1ab, thus enabling topology detection of devices that also have LLDP enabled.
Advantages of LLDP:
– Improved error localization
– Improved device replacement
– Efficient network configuration
When LLDP is enabled, the following information is received or transmitted:
– The device transmits its own management and connection information to neighboring
devices.
– The device receives management and connection information from a neighboring
device.
A port that is blocked via RSTP does not receive any LLDP BPDUs. It does send them,
however.
Function
A network infrastructure component transmits a port-specific BPDU (Bridge Protocol Data
Unit), at the interval set via "Message Transmit Interval" to each port in order to distribute
topology information. It contains the individual device information.
Through these BPDUs, the connected peer learns the respective neighbor information for
the specific port. The information learned is saved for a defined period of time (TTL, Time
To Live). If the same BPDUs are received again, the TTL value is increased again. The in-
formation therefore remains saved. If the TTL expires, the neighbor information is deleted.
– The switch manages a maximum of 50 items of neighbor information. Any information
beyond this is ignored.
– If several neighbors are displayed on one switch port, then at least one other switch
that does not support LLDP or in which LLDP is not enabled is installed between this
switch and the neighbor displayed.
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