Traffic Shaping; Traffic Policing - ZyXEL Communications SBG5500-A User Manual

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.
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.

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 SBG uses the Token Bucket
algorithm to allow a certain amount of large bursts while keeping a limit at the average rate.
Traffic Rate
Time
(Before Traffic Shaping)

Traffic Policing

Traffic policing is the limiting of the input or output transmission rate of a class of traffic on the basis of
user-defined criteria. Traffic policing methods measure traffic flows against user-defined criteria and
identify it as either conforming, exceeding or violating the criteria.
Traffic Rate
Time
(Before Traffic Policing)
The SBG supports three incoming traffic metering algorithms: Token Bucket Filter (TBF), Single Rate Two
Color Maker (srTCM), and Two Rate Two Color Marker (trTCM). You can specify actions which are
performed on the colored packets. See
metering algorithm.
Chapter 11 Bandwidth Management
Section 11.7 on page 207
SBG5500 Series User's Guide
195
Traffic Rate
Time
(After Traffic Shaping)
Traffic Rate
Time
(After Traffic Policing)
for more information on each