Some Network Considerations - NEC SL1100 Networking Manual

NEC SL1100
13.8
Networking Manual
The following chart shows the supported CODECS for IP phones with different
packet sizes over PPP and Ethernet.
CODEC
G.711
G.711
G.711
G.711
G.722
G.722
G.722
G.722
G.729
G.729
G.729
G.729
G.729
G.729

Some Network Considerations

When adding the SL1100 to a customers network there are many things to be
aware of. Before implementation a detailed network diagram of the existing
network must be obtained from the customer. This diagram may provide you
with information about possible 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,
providing 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.
Packet Size
10 103.2 kbps
20
30
40
10 103.2 kbps
20
30
40
10
20
30
40
50
60
PPP Ethernet
110.4 kbps
83.6 kbps 87.2 kbps
77.1 kbps 79.5 kbps
73.9 kbps 75.6 kbps
110.4 kbps
83.6 kbps 87.2 kbps
77.1 kbps 79.5 kbps
73.9 kbps 75.6 kbps
47.2 kbps 54.4 kbps
27.6 kbps 31.2 kbps
21.1 kbps 23.5 kbps
17.8 kbps 19.6 kbps
15.9 kbps 17.3 kbps
14.5 kbps 15.7 kbps
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