Avaya BCM 2.0 IP Telephony Bedienungsanleitung PDF herunterladen (Seite 22)

22 Engineering guidelines

Enterprise Edge 2.0 IP Telephony Configuration Guide P0911590 Issue 02

With Table 2 LAN and WAN IP bandwidth usage per Enterprise Edge Gateway

(loaded to 36 CCS per port per hour) without silence compression on page 21, for

calls without silence compression, each fax call generates 180.8 kbit/s. If all four

ports are in use for fax calls, then the additional load is 723.2 kbit/s. For more

information about fax calls, see the Fax calls section on page 41.

WAN engineering

To get traffic to Wide Area Network (WAN), use the formula: 0.5 x IP packet in

bytes x 8 x 1000/payload in ms. The reason for the reduction data rate is because of

the type of a duplex channel on a WAN. For example, with G.711 codec, a two-way

conversation channel has a rate of 128 kbit/s. However, the same conversation on

WAN (for example, a T1) requires a 64 kbit/s channel only, because a WAN

channel is a full duplex channel.

Both “talk” and “listen” traffic use a part of the 10 Mbit/s Ethernet channel while a

conversation uses a 64 kbit/s (DS0) duplex channel in a T1 or other WAN media.

Example 1: WAN engineering  voice calls

Consider a site with four IP telephony ports. The Preferred codec is G.723.1,

6.3 kbit/s, using a voice payload of 30 ms. Silence compression is enabled.

Given the above, what is the peak traffic in kbit/s that IP telephony will put on the

WAN?

With Table 1 LAN and WAN IP bandwidth usage per Enterprise Edge Gateway

(loaded to 36 CCS per port per hour) with silence compression on page 20, for

silence compression, each port generates 8.5 kbit/s when engaged in a call. If all

four ports are in use, then the additional load is 34 kbit/s.

Example 2: WAN engineering  fax calls

Consider a site with four IP telephony ports. The G.711 codec automatically

selected, with a voice payload of 20 ms. Silence compression is not used in the

G.711 codec.

With Table 2 LAN and WAN IP bandwidth usage per Enterprise Edge Gateway

(loaded to 36 CCS per port per hour) without silence compression on page 21, for

no silence compression, each port generates 80 kbit/s when engaged in a call. If all

four ports are in use, then the additional load is 320 kbit/s.

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