Traffic Management - CCIE Routing and Switching Exam Certification Guide - page 533

Foundation Summary

The Foundation Summary is a condensed collection of material that provides a convenient
review of key concepts in this chapter. If you are already comfortable with the topics in this
chapter, this summary will help you recall a few details. If you just read the Foundation Topics
section, this review should help solidify some key facts. If you are doing your final preparation
before the exam, these materials are a convenient way to review the day before the exam.

Queuing Strategies Table 11-4

Queuing
Strategies Description

FIFO First packet in, first packet out

PQ Prioritizes traffic into high, medium, normal, or low queues

CQ Prioritizes traffic with up to 16 queues, each queue is assigned a byte count limitation

WFQ Queues packets based on the arrival time of the last bit rather than the first bit, which

ensures that applications that use large packets cannot unfairly monopolize the
bandwidth

CBWFQ Uses IP Precedence bits in the ToS field or configured QoS groups to prioritize traffic

QoS and Traffic Mechanisms Summary
•

A host uses the RSVP protocol to request specific qualities of service from the network
for particular application data streams or flows.

•

MPLS fuses the intelligence of Layer-3 routing protocols with the speed of Layer-2
switching protocols. MPLS provides methods to perform traffic engineering, to guarantee
bandwidth, and to further enable Virtual Private Networks (VPNs).

•

GTS reduces outbound traffic flow to avoid congestion by constraining specified traffic to
a particular bit rate. It is configured with the following command:

traffic-shape rate bit-rate [burst-size [excess-burst-size]]

•

FRTS-enabled routers use received BECN information as input to manage the outbound
traffic. Traffic is shaped to the specified rate, not limited. It is configured by creating
classes of traffic and applying them to the interface with the frame-relay class command.

•

CAR provides the means to limit the input or output transmission rate on an interface or
subinterface based on traffic sources and destinations, while specifying policies for
handling traffic that exceeds bandwidth allocations. It is configured with the following
command:

rate-limit {input | output} [access-group [rate-limit]
acl-index | qos-group number] bps burst-normal burst-max
conform-action action exceed-action action