Link Layer Discovery Protocol (LLDP)
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8 Link Layer Discovery Protocol (LLDP)
8.1 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.
Displaying LLDP informa-
tion
The information that is collected is presented in a table in WBM. The table includes the two
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 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 in order to distribute topology information. The 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.
Please note that a blocking port using RSTP does not receive LLDP BPDUs, but does
send them.
The switch manages a maximum of 50 items of neighborhood information, all other infor-
mation is ignored.
If several neighbors are displayed on one switch port, then at least one other switch/hub,
which does not support or has not activated LLDP, is installed between this switch and
the neighbor indicated.
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