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Software User's
Manual
–
Version 3.0
Configuration > LLDP > LLDP-MED
LLDP-MED Configuration
This page allows you to configure the LLDP-MED. This function applies to VoIP devices which support
LLDP-MED.
Fast start repeat count
Rapid startup and Emergency Call Service Location Identification Discovery of endpoints are critically
important aspects of VoIP systems. In addition, it is best to advertise only those pieces of information
which are specifically relevant to particular endpoint types (for example only advertise the voice
network policy to permitted voice-capable devices). This is in order to conserve the limited LLDPU
space and to reduce security and system integrity issues that can come with inappropriate knowledge
of the network policy.
With this in mind, LLDP-MED defines an LLDP-MED Fast Start interaction between the protocol and
the application layers on top of the protocol in order to achieve these related properties. Initially, a
Network Connectivity Device will only transmit LLDP TLVs in an LLDPDU. Only after an LLDP-MED
Endpoint Device is detected, will an LLDP-MED capable Network Connectivity Device start to
advertise LLDP-MED TLVs in outgoing LLDPDUs on the associated interface. The LLDP-MED
application will temporarily speed up the transmission of the LLDPDU to start within a second when a
new LLDP-MED neighbor has been detected in order to share LLDP-MED information as fast as
possible to new neighbors.
Because there is a risk of an LLDP frame being lost during transmission between neighbors, it is
recommended to repeat the fast start transmission multiple times to increase the possibility of the
neighbors receiving the LLDP frame. With Fast start repeat count, it is possible to specify the
number of times the fast start transmission would be repeated. The recommended value is 4 times,
given that 4 LLDP frames with a 1 second interval will be transmitted, when an LLDP frame with new
information is received.
It should be noted that LLDP-MED and the LLDP-MED Fast Start mechanism is only intended to run
on links between LLDP-MED Network Connectivity Devices and Endpoint Devices, and as such does
not apply to links between LAN infrastructure elements including Network Connectivity Devices or
other types of links.