User manual

4200 User Manual Edgewater Networks, Inc.

Version 2.2 30

Traffic Management Configuration

Traffic management is required to ensure high quality voice calls when both voice

and data traffic share the same WAN link. Voice traffic must be prioritized for

transmission over data traffic to meet the stringent jitter, latency and packet loss

requirements for toll quality voice. The 4200:

 Automatically prioritizes voice traffic over data traffic to ensure toll quality

voice calls.

 Manages bandwidth using different upstream and downstream link speeds

(e.g. ADSL).

 Maximizes WAN link utilization by allowing data traffic to burst up to full line

rate in the absence of voice calls.

 Controls the data transfer rate of upstream TCP devices to limit WAN link

congestion.

 Optimizes throughput for low-bandwidth WAN links (eg. ADSL) by

automatically adjusting the Maximum Transmission Unit (MTU) and Maximum

Segment Size of IP datagrams during periods of WAN congestion.

 Supports network-based QoS applications by setting the TOS bits for all VoIP

packets sent to the WAN and the LAN. TOS bits are used so that VoIP packets

can be prioritized in the network by DiffServ enabled routers. The TOS bit

value used by the 4200 is to “minimize delay and maximize throughput” or 8p

hexadecimal. This value is set for all VoIP packets processed by the 4200 and

overwrites any specific TOS bit configuration set by VoIP endpoints.

 Ensures that bandwidth allocated to new voice calls does not adversely affect

the quality of existing active calls (Call Admission Control or CAC).

The 4200 combines sophisticated traffic management mechanisms including

classification, prioritization, queuing, rate limiting and CAC to ensure toll quality

voice calls. Fortunately the system manages this complexity for you and configuring

traffic management is very straightforward:

1. Enable traffic shaping.

2. Specify the upstream and downstream bandwidth of your WAN link.

3. Enable CAC.

Please follow steps A through H below to configure and

enable traffic management.

Enable Traffic Shaping

A. Select Traffic Shaper.

B. Select the Enable traffic shaper checkbox.

Specify the upstream and downstream

bandwidth of your WAN link

C. Enter the WAN Downstream Bandwidth in

Kbps.

D. Enter the WAN Upstream Bandwidth in Kbps.

If you are unsure of the WAN link bandwidth available