Class Rules; Figure 8-5: Qos - Edit Device Traffic Shaping - Edit Class - Add Traffic Priority Rule - AudioCodes MP-202 User Manual

8.1.2.1

Class Rules

Class rules define which packets belong to the class. They must be defined in order to
associate packets that meet them with the shaping class. Without class rules, the shaping
class will have no effect whatsoever. Each class can have outbound and/or inbound rules,
for outgoing and incoming traffic respectively. For example, you can define that all outgoing
packets from computer A in your LAN belong to your VoIP class. These packets will be
limited to the class settings (bandwidth, schedule, etc.). In addition, you can define the
traffic protocol and priority for each rule (this is not mandatory as in Traffic Priority rules).
8.1.2.1.1 Inbound and Outbound Data
The gateway can control outgoing data easily. It can queue packets, delay them, give
precedence to other packets, or drop them. This helps in resolving upload (Tx) traffic
bottlenecks and in most cases is sufficient. However, in the case of download (Rx) traffic
bottlenecks, the ability to control the flow is much more limited. The gateway cannot queue
packets, since in most cases the LAN is much faster then the WAN, and when the gateway
receives a packet from the WAN, it passes it immediately to the LAN.
QoS for ingress data has the following limitations, which do not exist for outgoing data:
QoS can only be applied to TCP streams (UDP streams cannot be delayed).
No borrowing mechanism.
When reserving Rx bandwidth, it is strictly taken from the bandwidth of all other
classes.
Furthermore, the gateway cannot control the behavior of its WAN gateway (usually the
ISP), which may not have proper QoS handling. Unfortunately, this is a common situation.
Let's look at a scenario of downloading a large file and surfing the Internet at the same
time. Downloading the file is distinguished by small requests, followed by very large
responses. This may result in blocking HTML traffic at the ISP. A solution for such a
situation is limiting the bandwidth of low-priority TCP connections (such as the file
download).
To add a new outbound/inbound class rule:
1. In the screen 'Edit Class' under the screen section 'Class Rules', click link 'New Entry';
the screen 'Add Traffic Priority Rule' opens (refer to the figure).

Figure 8-5: QoS - Edit Device Traffic Shaping - Edit Class - Add Traffic Priority Rule

MP-202 Telephone Adapter 66
MP-202
LTRT-50604