Planet GS-5220 Series User Manual page 464

Fast start repeat
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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 apply to links between LAN infrastructure elements, including
Network Connectivity Devices, or other types of links.
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User's Manual of GS-5220 LCD Series