Chapter 14 - QoS Flashcards
Which of the following is not a QoS implementation model?
A - IntServ
B - Expedited forwarding
C - Best effort
D - DiffServ
B -
Best effort, IntServ, and DiffServ are the three QoS implementation models.
Which traffic conditioning tool can be used to drop or mark down traffic that goes beyond a desired traffic rate?
A - Policers
B - Shapers
C - WRR
D - None of the above
A
The 16-bit TCI field is composed of which fields? (Choose three.)
A - Priority Code Point (PCP)
B - Canonical Format Identifier (CFI)
C - User Priority (PRI)
D - Drop Eligible Indicator (DEI)
E - VLAN Identifier (VLAN ID)
A, D and E
The TCI field is a 16-bit field composed of the 3-bit Priority Code Point (PCP) field (formerly PRI), the 1-bit Drop Eligible Indicator (DEI) field (formerly CFI), and the 12-bit VLAN Identifier (VLAN ID) field.
Which of the following are the recommended congestion management mechanisms for modern rich-media networks? (Choose two.)
A - Class-based weighted fair queuing (CBWFQ)
B - Priority queuing (PQ)
C - Weighted RED (WRED)
D - Low-latency queuing (LLQ)
A and D
CBWFQ and LLQ provide real-time, delay-sensitive traffic bandwidth and delay guarantees while not starving other types of traffic.
True or false: The DiffServ field is an 8-bit Differentiated Services Code Point (DSCP) field that allows for classification of up to 64 values (0 to 63).
False
The IPv4 ToS field and the IPV6 traffic class field were redefined as an 8-bit Differentiated Services (DiffServ) field. The DiffServ field is composed of a 6-bit Differentiated Services Code Point (DSCP) field that allows for classification of up to 64 values (0 to 63) and a 2-bit Explicit Congestion Notification (ECN) field.
Which of the following is a recommended congestion-avoidance mechanism for modern rich-media networks?
A - Weighted RED (WRED)
B - Tail drop
C - FIFO
D - RED
A
What does Tc stand for? (Choose two.)
A - Committed time interval
B - Token credits
C - Bc bucket token count
D - Traffic control
A and C
The Committed Time Interval (Tc) is the time interval in milliseconds (ms) over which the Committed Burst (Bc) is sent. Tc can be calculated with the formula Tc = (Bc [bits] / CIR [bps]) × 1000. For single-rate three-color markers/policers (srTCMs) and two-rate three-color markers/policers (trTCMs), Tc can also refer to the Bc Bucket Token Count (Tc), which is the number of tokens in the Bc bucket.
Network latency can be broken down into which of the following types? (Choose all that apply.)
A - Propagation delay (fixed)
B - Time delay (variable)
C - Serialization delay (fixed)
D - Processing delay (fixed)
E - Packet delay (fixed)
F - Delay variation (variable)
A, C, D and F
Network latency can be broken down into propagation delay, serialization delay, processing delay, and delay variation.
Which of the following is the QoS implementation model that requires a signaling protocol?
A - IntServ
B - Best Effort
C - DiffServ
D - RSVP
A
Which of the following are the leading causes of quality of service issues? (Choose all that apply.)
A - Bad hardware
B - Lack of bandwidth
C - Latency and jitter
D - Copper cables
E - Packet loss
B, C and E
The leading causes of quality of service issues are lack of bandwidth, latency and jitter, and packet loss.
Which of the following is the most popular QoS implementation model?
A - IntServ
B - Best effort
C - DiffServ
D - RSVP
C
DiffServ is the most popular and most widely deployed QoS model. It was designed to address the limitations of the best effort and IntServ.
True or false: Traffic classification should always be performed in the core of the network.
False
Need to more closer to the source.
