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Link Layer Discovery Protocol (LLDP)
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7 Link Layer Discovery Protocol (LLDP)
7.1 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 or sent to neighbors, as long as LLDP is activated:
– The device transmits its own management and connection information to neighboring
devices.
– The device receives management and connection information from neighboring devic-
es.
LLDP general The Link Layer Discovery Protocol (LLDP) according to 802.1ab is used by network devices
to learn and maintain the individual neighborhood relationships.
Function
A network infrastructure component transmits a port-specific BPDU (Bridge Protocol Data
Unit), which contains the individual device information, at the “Message Transmit Interval”
to each port to distribute topology information. The remote peer 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 known as the
TTL (Time To Live) value. Subsequent receipt of the same BPDUs increases the TTL value
again and the information is still saved. When the TTL elapses, the neighbor information is
deleted.
An IRT switch manages a maximum of 15 items of neighbor information, all other informa-
tion is ignored.
If several neighbors are displayed on one switch port, then at least one other switch/hub
that does not support or has not activated LLDP, is installed between this switch and the
neighbor indicated.