Configuring Qos Settings - Extreme Networks EPICenter Reference Manual

Voice over IP Manager
Table 66: Minimum Bandwidth Requirements and Calculations for VoIP VLAN
Compression
algorithm
G.711, rate=64 Kbps
G.711, rate=64Kbps
G.711, rate=64Kbps
G.711, rate=64Kbps
G.729, rate=8.0Kbps
G.729, rate=8.0Kbps
G.729, rate=8.0Kbps
G.729, rate=8.0Kbps
G.723.1, rate=6.4Kbps
G.723.1, rate=6.4Kbps
G.723.1, rate=6.4Kbps
G.723.1, rate=6.4Kbps
The first two columns of
●
number of IP phone ports.
The third column shows the total bandwidth requirement calculated based on the compression rate
●
and number of ports as shown in the first two columns.
The fourth column (Min bandwidth needed for egress ports) shows the corresponding minimum
●
bandwidth that should be configured for a gigabit egress port such as the egress port on the
upstream switch.
The last column shows the actual maximum number of simultaneous calls that can be supported by
●
the minimum bandwidth.
Find the minimum bandwidth setting in the table that corresponds to your VoIP setup (number of
phones and compressions algorithm. Then, make sure the minimum bandwidth setting for the VLAN
on your upstream switch(es) meets this requirement. You can change the bandwidth settings for an
individual switch using the Configure VoIP QoS Parameters dialog. See
page 560 for more information.
Note that the bandwidth calculation algorithm always assumes there is a one-to-one correspondence
between the number of IP phones and the number of ingress ports included in the VoIP VLAN.
Another situation that may result in an incorrect bandwidth calculation is where multiple IP phone are
connected via a hub to a single ingress port on a switch. In this configuration the VoIP Manager will
underestimate the number of IP phone connections, and will therefore underestimate the required
minimum bandwidth. In this case, you can also use the information in
the correct minimum bandwidth in the QoS profile for the VoIP VLAN on the switch.

Configuring QoS Settings

Changing the default configuration attributes does not actually configure any settings on the switches.
The information is provided to simplify the configuration task for the user and to recommend
560
Number of Total calculated
phones bandwidth
(one per port)
0~100 0~7 Mbps
100~200 7~13 Mbps
200~300 13~20 Mbps
300~400 20~26 Mbps
0~100 0~1 Mbps
100~200 1~2 Mbps
200~300 2~3 Mbps
300~400 3~4 Mbps
0~100 0~1 Mbps
100~200 1~2 Mbps
200~300 2 Mbps
300~400 2~3 Mbps
Table 66 show various combinations of the compression algorithms and
Min bandwidth Max number
needed for egress ports of phones
supported
10 Mbps (Min=1%) 156
20 Mbps(Min=2%) 312
20 Mbps(Min=2%) 312
30 Mbps(Min=3%) 468
10 Mbps(Min=1%) 1250
10 Mbps(Min=1%) 1250
10 Mbps(Min=1%) 1250
10 Mbps(Min=1%) 1250
10 Mbps(Min=1%) 1562
10 Mbps(Min=1%) 1562
10 Mbps(Min=1%) 1562
10 Mbps(Min=1%) 1562
"Configuring QoS Settings" on
Table 66 to help you determine
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