ZyXEL P-2802HW-I1 User Guide - Page 239
QoS Overview
View all ZyXEL P-2802HW-I1 manuals
Add to My Manuals
Save this manual to your list of manuals |
Page 239 highlights
CHAPTER 17 Quality of Service (QoS) This chapter contains information about configuring QoS, editing classifiers and viewing the ZyXEL Device's QoS packet statistics. 17.1 QoS Overview Quality of Service (QoS) refers to both a network's ability to deliver data with minimum delay, and the networking methods used to control the use of bandwidth. Without QoS, all traffic data is equally likely to be dropped when the network is congested. This can cause a reduction in network performance and make the network inadequate for time-critical application such as video-on-demand. Configure QoS on the ZyXEL Device to group and prioritize application traffic and fine-tune network performance. Setting up QoS involves these steps: 1 Configure classifiers to sort traffic into different flows. 2 Assign priority and define actions to be performed for a classified traffic flow. The ZyXEL Device assigns each packet a priority and then queues the packet accordingly. Packets assigned a high priority are processed more quickly than those with low priority if there is congestion, allowing time-sensitive applications to flow more smoothly. Timesensitive applications include both those that require a low level of latency (delay) and a low level of jitter (variations in delay) such as Voice over IP (VoIP) or Internet gaming, and those for which jitter alone is a problem such as Internet radio or streaming video. 17.1.1 IEEE 802.1Q Tag The IEEE 802.1Q standard defines an explicit VLAN tag in the MAC header to identify the VLAN membership of a frame across bridges. A VLAN tag includes the 12-bit VLAN ID and 3-bit user priority. The VLAN ID associates a frame with a specific VLAN and provides the information that devices need to process the frame across the network. IEEE 802.1p specifies the user priority field and defines up to eight separate traffic types. The following table describes the traffic types defined in the IEEE 802.1d standard (which incorporates the 802.1p). Table 98 IEEE 802.1p Priority Level and Traffic Type PRIORITY LEVEL TRAFFIC TYPE Level 7 Typically used for network control traffic such as router configuration messages. Level 6 Typically used for voice traffic that is especially sensitive to jitter (jitter is the variations in delay). P-2802H(W)(L)-I Series User's Guide 239