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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 mismatch
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:
1. Layer 2 VLAN ID (IEEE 802.1Q-2003)
2. Layer 2 priority value (IEEE 802.1D-2004)
3. 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:
1. Voice
2. Guest Voice
3. Softphone Voice
4. Video Conferencing
5. Streaming Video
6. Control / Signalling (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.
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