NEC NEAX 2000 IPS Reference Manual page 291

Chapter 13 Voice Over IP (VoIP)
Quality of Service (QoS)
In order to obtain quality of service (QoS) for the voice traffic, routers or layer 3 switches in the
network must support a queuing mechanism. The queuing mechanism allows for the
prioritization of the voice packets to pass through the router before the routine data traffic. The
NEAX PBX system allows for customizing the priority of the voice traffic out of the PBX. This
prioritization occurs with the IP precedence bits inside the IP header. With a higher level of
prioritization, the voice traffic will not accumulate as much delay as traffic with lower levels of
priority. With Diff-Serve (Differentiated Services), prioritization can be made if the routing
devices support it. NEAX PBX IP trunks support Diff-Serve.
QoS should be pushed as close to the network edge as possible. At the edge, this is
considered CoS (Class of Service). A layer 2 switched environment is recommended to obtain
full throughput to a routing device for NEAX IP telephony and for CoS management.
Specific ports on the data switch may be prioritized for QoS or CoS. If this is available, the port
that is connected to a NEAX IP telephony device should be prioritized in this manner.
Additionally in the network, the port that has been prioritized, in the above manner, must also
be set as a trusted value in the network. When CoS is used on the edge, map it to a higher
level (layer 3) QoS value. This mapping allows for a consistent prioritization throughout the
entire network. By using the prioritization methods described for the PBX and the network
optimal data transfer in the core and edge devices throughout the network may be
accomplished.
Device Registration Server (DRS) and DHCP
The Device Registration Server (DRS) is built into the MP card (System-based DRS). The
System-based DRS can provide log-in/log-out function and registration authorization function
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of IP Enabled D terminals. Up to 952 IP Enabled D terminals can be managed by the
System-based DRS. Once the Device Registration Server (DRS) is located, depending on the
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configuration chosen, the IP Enabled D will prompt for a login and password. Network-
based DRS (external DRS) 3.0 is not supported.
DHCP (Dynamic Host Configuration Protocol) can be used for ease of administration for IP
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Enabled D terminals in the network. The IP adapter can be set to use a DHCP server to
supply its IP address and the address of the DRS. Network administrators can set up the
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option in the DHCP server to give the IP Enabled D terminal the information needed to find
the DRS.
NEAX 2000 IPS Request for Proposal (RFP) Reference Guide Page 13- 33
NDA-24349, Issue 4