Edgewater Networks 4200 Series - A Closer Look at Traffic Management in the 4200

4200 User Manual Edgewater Networks, Inc.
Version 3.0 86
(768*.85)/85.6 = 7.6 or 7 total voice calls
The maximum number of G.711 voice calls supported by an ADSL WAN with 768Kbps
downstream WAN bandwidth and 256Kbps upstream WAN bandwidth is calculated as
follows:
(256*.85)/85.6 = 2.5 or 2 total voice calls
The maximum number of G.729 voice calls supported by an ADSL WAN with 768Kbps
downstream WAN bandwidth and 256Kbps upstream WAN bandwidth is calculated as
follows:
(256*.85)/29.6 = 7.4 or 7 total voice calls
After determining the maximum number of voice calls CAC is enabled as follows:
F. Select the Enable Call Admission Control checkbox.
G. Enter Maximum number of calls allowed as calculated above.
H. Press Submit.
A Closer Look at Traffic Management in the 4200
The traffic management mechanisms provided by the 4200 are designed to ensure
high priority real time voice traffic is processed before lower priority data traffic. At
the same time, bandwidth not in use by voice traffic is made available so that data
traffic can burst up to full line rate making efficient use of WAN bandwidth. Traffic
management mechanisms are applied to traffic in both the upstream (LAN to WAN)
and downstream (WAN to LAN) direction. Each direction is independent of the other
and can support different size priority queues. This is particularly useful in the case
of ADSL where the downstream bandwidth is greater than the upstream bandwidth
and it would be undesirable to limit downstream data traffic to the rate of the slower
upstream link.
Classifying
High priority voice traffic generated by endpoint devices such as IP phone and client
adaptors are identified by their IP address. The user configures these addresses into
a priority list using the traffic shaping section of the 4200 web GUI. As the 4200
processes packets they are marked as either high or low priority based on this
configuration.
Upstream Traffic Management
The 4200 appliance uses a combination of Class Based Queuing and simple classless
queuing to send data in the upstream direction. The Class Based Queue (CBQ)
consists of two priority classes (high and low), a scheduler to decide when packets
need to be sent earlier than others and a traffic shaper to rate limit by delaying
packets before they are sent. Voice traffic is placed in the high priority class and
data traffic is placed in the low priority class. High priority data is sent out at up to
the configured priority data rate and this class is polled before lower priority data to