Black Box LGB1108A, LGB1126A, LGB1148A manual Page, 44. The LLDP-MED Configuration screen

Chapter 3: Configuration

Figure 3-44. The LLDP-MED Configuration screen.

Figure 3-45 The LLDP-MED Configuration Policies screen .

Parameter Description Fast start repeat count

The Rapid startup and Emergency Call Service Location Identification Discovery of endpoints are critically important aspects of VoIP systems. It is best to advertise only those pieces of information that are specifically relevant to particular endpoint types (for example only advertise the voice network policy to permitted voice-capable devices), both 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 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 neighbor has been detected 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, Black Box recommends that you repeat the fast start transmission multiple times to increase the possibility of the neighbors receiving the LLDP frame. With the fast start repeat count selection, it is possible to specify the number of times the fast start transmission would be repeated. The rec- ommended 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.

NOTE: The LLDP-MED and the LLDP-MED Fast Start mechanism are only intended to run on links between LLDP-MED Network connectivity Devices and Endpoint Devices, and as such do not apply to links between LAN infrastructure elements, including network connectivity devices, or other types of links.

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