Nortel Remote Office 9150 Installation And Administration Manual page 406

Network engineering guidelines
4 Calculate average bandwidth use on TLAN
For voice:
720/36*30.7 = 614 Kbps
According to the table on page 376, the data output for G.729 Annex AB
and 30 ms payload is 30.7 Kbps.
For fax:
84/36*46.1 =108 Kbps
Total bandwidth = 614 + 108 = 722 Kbps
5 Adjust requirement for traffic peaking
Peak hour bandwidth requirement = 722*1.3 = 939 Kbps
This is the spare bandwidth that a TLAN should have to handle the VoIP
and fax traffic. Nortel Networks recommends that the TLAN handle Remote
Office traffic exclusively.
Note: This example is based on the G.729 Annex AB codec with 30 ms payload
size. For relations of user selectable parameters (for example, payload size,
codec type, packet size, and QoS), refer to "Setting the Quality of Service" on
page 398.
General LAN and WAN engineering considerations
The TLAN traffic capacity does not limit Remote Office network engineering.
Refer to standard Ethernet engineering tables for passive 10BaseT repeater hubs.
Refer to manufacturer's specifications for intelligent 10BaseT layer switches.
A passive 10BaseT Ethernet hub is a half-duplex data transport mechanism.
Both "talk" and "listen" traffic use a part of the nominal 10 Mbps capacity. You
must set up the passive 10BaseT Ethernet hub so that TLAN voice traffic does
not exceed 3 Mbps on a 10BaseT Ethernet. A 10BaseT Ethernet switch port can
operate in either half-duplex or full-duplex mode, but Remote Office Ethernet
interfaces operate only in half-duplex mode. A switched Ethernet hub can reach
throughput of 10 Mbps. For more information, refer to your manufacturer's
specifications.
Due to its high capacity, 100BaseT Ethernet does not experience bottlenecks.
380
Standard 1.0
Remote Office 9150