System information

109
LLDP Media 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 is a critically
important aspect of VoIP systems in general. 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), both 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 port. The LLDP-MED application will
temporarily speed up the transmission of the LLDPDU to start within a second, when a new LLDP-MED
neighbour has been detected in order share LLDP-MED information as fast as possible to new
neighbours.
Because there is a risk of an LLDP frame being lost during transmission between neighbours, it is
recommended to repeat the fast start transmission multiple times to increase the possibility of the
neighbours 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