ZyXEL Communications VSG1432-B101 Series Manual Do Utilizador
Chapter 10 Quality of Service (QoS)
VSG1432-B101 Series User’s Guide
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• The Monitor screen lets you view the ZyXEL Device's QoS-related packet
statistics (
10.2 What You Need to Know
The following terms and concepts may help as you read through this chapter.
QoS versus Cos
QoS is used to prioritize source-to-destination traffic flows. All packets in the same
flow are given the same priority. CoS (class of service) is a way of managing traffic
in a network by grouping similar types of traffic together and treating each type as
a class. You can use CoS to give different priorities to different packet types.
flow are given the same priority. CoS (class of service) is a way of managing traffic
in a network by grouping similar types of traffic together and treating each type as
a class. You can use CoS to give different priorities to different packet types.
CoS technologies include IEEE 802.1p layer 2 tagging and DiffServ (Differentiated
Services or DS). IEEE 802.1p tagging makes use of three bits in the packet
header, while DiffServ is a new protocol and defines a new DS field, which replaces
the eight-bit ToS (Type of Service) field in the IP header.
Services or DS). IEEE 802.1p tagging makes use of three bits in the packet
header, while DiffServ is a new protocol and defines a new DS field, which replaces
the eight-bit ToS (Type of Service) field in the IP header.
Tagging and Marking
In a QoS class, you can configure whether to add or change the DSCP (DiffServ
Code Point) value, IEEE 802.1p priority level and VLAN ID number in a matched
packet. When the packet passes through a compatible network, the networking
device, such as a backbone switch, can provide specific treatment or service
based on the tag or marker.
Code Point) value, IEEE 802.1p priority level and VLAN ID number in a matched
packet. When the packet passes through a compatible network, the networking
device, such as a backbone switch, can provide specific treatment or service
based on the tag or marker.
Traffic Shaping
Bursty traffic may cause network congestion. Traffic shaping regulates packets to
be transmitted with a pre-configured data transmission rate using buffers (or
queues). Your ZyXEL Device uses the Token Bucket algorithm to allow a certain
amount of large bursts while keeping a limit at the average rate.
be transmitted with a pre-configured data transmission rate using buffers (or
queues). Your ZyXEL Device uses the Token Bucket algorithm to allow a certain
amount of large bursts while keeping a limit at the average rate.
Tr
af
fi
c
Time
Traffic Rate
Tr
a
ff
ic
Time
Traffic Rate
(Before Traffic Shaping)
(After Traffic Shaping)