C
HAPTER
4
| Configuring the Switch
Link Layer Discovery Protocol
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Postal community name - Postal community name.
(Example: Leonia)
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P.O. Box - Post office box (P.O. BOX). (Example: 12345)
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Additional code - Additional code. (Example: 1320300003)
◆ Emergency Call Service – Emergency Call Service (e.g. 911 and
others), such as 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
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Guest Voice
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Softphone Voice
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Video Conferencing
■
Streaming Video
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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.
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