QoS Flashcards
The measure of transmission quality and service availability of a network
QoS
Not real-time traffic. Bursty and widely varying packet arrival times.
Data Traffic
Real-time traffic. Constant and predictable bandwidth and packet arrival times. Packets are small but are delay sensitive and should be less than 150 ms.
Voice Traffic
Varied bandwidth requirements, can be real time but not always
Video Traffic
What are the quality issues in converged networks?
Lack of bandwidth End-to end delay Variation of delay (jitter) Packet loss
What QoS mechanism identifies and categorizes traffic into classes?
Classification and marking
QoS mechanism that controls the maximum rate of traffic sent or received on an interface.
Policing
What is the difference between policing and shaping?
Policing drops exceeding traffic
Shaping delays exceeding traffic
What QoS mechanism uses class-based weighted fair queue, which guarantees specific amount of bandwidth to different classes of traffic?
CBWFQ
Often configured on interfaces at the edge of a network to limit traffic and is typically used by service providers to offer customers sublate access
Policing
Bandwidth assigned to a class is the _____ bandwidth allocated to the class during congestion.
minimum
What congestion management or scheduling feature prioritizes voice traffic so it gets to the final destination first
Low-latency queue
QoS feature that allows certain types of connections, such as WAN links, to be provisioned with special traffic handling tools such as fragmentation.
Link-specific tools
A point in the network where packet markings are not necessarily trusted
Trust boundary
The network locations where packet markings are accepted and acted upon
Borders of a trust domain
Devices with user access such as PCs and printers are classified under the _____ domain
untrusted
Part of the network with only network administrator access such as routers and switches.
trusted domains
Tool that inspects packets within a field to identify the type of traffic that the packet is carrying
Classifier
What are the four policy-enforcement mechanisms?
Marking
Queing
Policing
Shaping
Tool that writes a value in the header of a packet, frame, cell, tag, or label
Marker
Layer 2 Ethernet marking that contains three bits to mark the Ethernet frames
Class of Service (CoS)
Describes a 3-bit field in the QoS control field of wireless frames
Traffic Identifier (TID)
Generally used to indicate the Layer 3 packet field. Comprised of 8 bits, 3 of which are designated as the IP precedence field
ToS (Type of Service)
Set of 6-bit values that is used to describe the meaning of ToS. It is backwards compatible with IP precendence.
DSCP (Differentiated services code point)
Where should classification and marking be performed?
Close to end devices