NEC Univerge SV9100 Manual page 492

Issue 2.0
SV9100 Networking Manual
General IP Configuration
The voice quality of VoIP depends on variables such as available bandwidth,
network latency, and quality of service initiatives (QoS), all of which are controlled
by the network and internet service providers. Because these variables are not in
NEC control, it cannot guarantee the performance of the users IP based voice
solution. Therefore, NEC recommends connecting the VoIP equipment through a
local area network using private IP addresses.
For a network to be suitable for VoIP it must pass specific requirements. To make
sure that the site meets these requirements, an IP ready check and a site survey
must be completed at each site before VoIP implementation.
One-way delay must not exceed 100ms.

Round-trip delay must not exceed 200ms.

Packet loss must not exceed 1%

Data switches must be manageable

Routers must provide QOS
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Adequate bandwidth for estimated VoIP traffic (refer to

Depending on how QoS policies are built in the network, assignments might be

needed in the CPU.
Some Network Considerations
Before adding the UNIVERGE SV9100 to a customer network, a detailed network
diagram of the existing network must be obtained from the customer. This
diagram provides information about any network conditions that can prevent or
hinder the VoIP equipment from functioning correctly.
Firewalls
Another regular device in customer networks that can hinder VoIP performance is
a firewall. Most corporate LANs connect to the public Internet through a firewall. A
firewall is filtering software built into a router or a stand alone server unit. It is used
to protect a LAN it from unauthorized access, to provide the network with a level
of security. Firewalls are used for many things, but in its simplest form, a firewall
can be thought of as a one-way gate. It allows outgoing packets from the local
LAN to the Internet but blocks packets from the Internet routing into the local LAN,
unless they are a response to query.
A firewall must be configured to allow specific traffic from the Internet to pass
through onto the LAN.
1.5.3 Bandwidth)
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