User manual

APS User Manual
141
Parameter Description
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 to 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 will be repeated. The recommended value is 4 times,
Fig. 64 LLDP-MED Configuration