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defined by TIA or NENA.
ELIN identifier data format is defined to carry the ELIN identifier as used during emergency
call setup to a traditional CAMA or ISDN trunk-based PSAP. This format consists of a
numerical digit string, corresponding to the ELIN to be used for emergency calling.
◆ Policies – Network Policy Discovery enables the efficient discovery and diagnosis of
mismatched issues with the VLAN configuration, along with the associated Layer 2 and
Layer 3 attributes, which apply for a set of specific protocol applications on that port.
Improper network policy configurations are a very significant issue in VoIP environments
that frequently result in voice quality degradation or loss of service.
Policies are only intended for use with applications that have specific “real-time” network
policy requirements, such as interactive voice and/ or video services.
The network policy attributes advertised are:
■ Layer 2 VLAN ID (IEEE 802.1Q-2003)
■ Layer 2 priority value (IEEE 802.1D-2004)
■ Layer 3 Diffserv code point (DSCP) value (IETF RFC 2474)
This network policy is potentially advertised and associated with multiple sets of application
types supported on a given port. The application types specifically addressed are:
■ Voice
■ Guest Voice
■ Softphone Voice
■ Video Conferencing
■ Streaming Video
■ Control / Signaling (conditionally support a separate network policy for the media types
above)
A large network may support multiple VoIP policies across the entire organization, and
different policies per application type. LLDP-MED allows multiple policies to be advertised
per port, each corresponding to a different application type. Different ports on the same
Network Connectivity Device may advertise different sets of policies, based on the
authenticated user identity or port configuration.
It should be noted that LLDP-MED is not intended to run on links other than between
Network Connectivity Devices and Endpoints, and therefore does not need to advertise the
multitude of network policies that frequently run on an aggregated link interior to the LAN.
■ Policy ID – ID for the policy. This is auto generated and will be used when selecting the
polices that will be mapped to the specific ports.
■ Application Type – Intended use of the application types:
■ Voice – For use by dedicated IP Telephony handsets and other similar appliances
supporting interactive voice services. These devices are typically deployed on a separate
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