Using Generic Traffic Shaping
and Frame Relay Traffic Shaping
Traffic shaping is a mechanism that restricts traffic going out an interface to a
particular speed and, at the same time, attempts to buffer bursts in excess of this
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Flow-Based Random Early Detection
Flow-Based RED (FRED) is an extension to WRED that ensures no single
flow can monopolize all the buffer resources at the output interface
queue. With normal WRED, a packet dropped from a TCP source causes
the source to reduce its transmission, whereas a packet dropped from a
noncompliant source, like UDP, does not. This may have the end effect
of the polite flows being drowned out by the impolite flows. Flow-based
RED prevents this by maintaining minimal information about the buffer
occupancy of each flow. In this way, when a flow exceeds its share of the
output buffer, it is dropped. This is in contrast to the more random
buffer drops of normal WRED. This feature first became available in IOS
version 12.0(3)T.
Designing & Planning…
252 Chapter 8 • Advanced QoS for AVVID Environments
maximum speed.Traffic shaping thereby acts to smooth out or shape traffic into a
stream that conforms to downstream requirements. Cisco offers two traffic shaping
features, namely, Generic Traffic Shaping (GTS) and Frame Relay Traffic Shaping
(FRTS).These two features are more similar than they are different.To understand
traffic shaping in general, let us first look at the fundamental algorithm behind it.