Chapter 6 - Qos - D-Link Xstack DES-3528 Series Reference Manual

xStack® DES-3528/DES-3552 Series Layer 2 Managed Stackable Fast Ethernet Switch Web UI Reference Guide
Chapter 6 -
802.1p Settings
Bandwidth Control
Traffic Control Settings
DSCP
HOL Blocking Prevention
Scheduling Settings
SRED
The Switch supports 802.1p priority queuing Quality of Service. The following section discusses the implementation
of QoS (Quality of Service) and benefits of using 802.1p priority queuing.
Advantages of QoS
QoS is an implementation of the IEEE 802.1p standard that allows network administrators a method of reserving
bandwidth for important functions that require a large bandwidth or have a high priority, such as VoIP (voice-over
Internet Protocol), web browsing applications, file server applications or video conferencing. Not only can a larger
bandwidth be created, but other less critical traffic can be limited, so excessive bandwidth can be saved. The
Switch has separate hardware queues on every physical port to which packets from various applications can be
mapped to, and, in turn prioritized. View the following map to see how the Switch implements basic 802.1p priority
queuing.
The picture above shows the 802.1p user priority setting for the Switch. As Class-7 is used for stacking function,
Class-6 has the highest priority of the seven priority classes of service on the Switch. In order to implement QoS,
the user is required to instruct the Switch to examine the header of a packet to see if it has the proper identifying
tag. Then the user may forward these tagged packets to designated classes of service on the Switch where they
will be emptied, based on priority.
QoS
Figure 6-1 Mapping QoS on the Switch
156