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2013 Latest Cisco 350-001 Exam Section 1: Traffic Classification (18 Questions)

QUESTION NO: 1
You want traffic on your frame relay link to conform to specific policies. Because of this, you configure traffic shaping as follows:
Router configuration:

ip cef

class-map match-all gold
match ip dscp 10 12 14
class-map match-all bronze
match ip dscp 26 28 30
class-map match-all silver
match ip dscp 18 20 22

policy-map SHAPE
class gold
shape peak 512000
bandwidth percent 50
class bronze
shape average 384000
bandwidth percent 20
class silver
bandwidth percent 30
shape peak 448000

interface Serial4/0
encapsulation frame-relay
ip address 14.34.34.51 255.255.255.0
service-policy output SHAPE

end

You verify your configuration using the “show policy-map” command as shown below:
RouterTestK#sh policy-map inter s4/0

Serial4/0

Service-policy output: SHAPE (1865)

Class-map: gold (match-all) (1866/2)

0 packets, 0 bytes
1 minute offered rate 0 bps, drop rate 0 bps
Match: ip dscp 10 12 15 (1868)
Traffic Shaping
Target Byte Sustain Excess Interval Increment Adapt
Rate Limit bits/int bits/int (ms) (bytes) (active)
1024000 3200 12800 12800 25 3299 –
Queue Packets Bytes Packets Bytes
Depth Delayed Delayed Active
0 0 0 0 no

Weighted Fair Queueing

Output Queue: Conversation 265
Bandwidth 50% Max Threshold 64 (packets)
(pkts matched/bytes matched) 0/0
(pkts discards/bytes discards/tail drops) 0/0/0

Based on this information, what is the CIR value for all the traffic marked with DSCP values 10?
A. 128000
B. 256000
C. 512000
D. 1024000
E. Cannot be determined
Answer: D
Explanation:
In shape peak you should use the formula: Peak Rate = AvgRate * (1+Be/Bc)
That will be 1024000 for the config 512000
Not C: 512000 is alright if it was shape average.

QUESTION NO: 2 What are the primary reasons to implement traffic shaping on a network? (Choose all that apply).
A. To regulate and thus control the average queue size by indicating when transmission of packets should be halted temporarily.
B. To control access to available bandwidth on the network.
C. To define Layer 3 aggregate or granular bandwidth rate limits.
D. To control the maximum rate of traffic on an interface.
E. To ensure that traffic conforms to the policies established for it.
F. To prevent denial of service attacks.
G. To drop high levels of unwanted traffic.
Answer: B, E
Explanation:
According to Cisco, the primary reasons to use traffic shaping are to control access to available bandwidth, to ensure that traffic conforms to specific policies, and to regulate the flow of traffic in order to avoid congestion. Reference: http://www.cisco.com/univercd/cc/td/doc/product/lan/cat4224/sw_confg/traffic.htm

QUESTION NO: 3
You have set up priority queuing on the serial interface of your router as follows:
priority-list 1 protocol ip high list 101
priority-list 1 protocol ip medium list 102
priority-list 1 protocol ip normal list 103
priority-list 1 protocol ip low list 104
priority-list 1 default low

access-list 101 permit ip any any precedence critical
access-list 102 permit ip any any precedence flash
access-list 103 permit ip any any precedence priority
access-list 104 permit ip any any precedence network

A packet reaches the router with an IP Precedence value of 4. What priority will this packet be assigned by the router?
A. Low
B. Normal
C. Medium
D. High
E. Critical

F. Flash
Answer: A
Explanation:
The IP precedence values are shown below:
0 : routine
1 : priority
2 : immediate
3 : flash
4 : flash Override
5 : critical
6 : internet
7 : network
In this example, IP precedence 4 (flash override) was not explicitly defined in the priority list, so it will be handled by the default queue. In this case, the default queue is given a priority of low.

QUESTION NO: 4
A Testking router’s interface is configured for traffic shaping as follows:
interface Serial1.1 point-to-point ip address 10.16.1.1 255.255.255.252 frame-relay class Testking frame-relay interface-dlci 220 ! ! map-class frame-relay Testking frame-relay cir 128000 frame-relay bc 8000 frame-relay be 8000 no frame-relay adaptive-shaping
In what are the bc and be parameters measured in the above configuration?
A. Bits per millisecond.
B. Bits per interval.
C. Bytes per interval.
D. Bytes per second.
E. Bits per second.
F. Bytes per millisecond.
Answer: B
Explanation:
The Sustain (bc) and excess (be) are configured bit per interval.
The following is sample output of the show traffic-shape command:

Target Rate = CIR = 100000 bits/s
Mincir = CIR/2 = 100000/2 = 50000 bits/s
Sustain = Bc = 8000 bits/int
Excess = Be = 8000 bits/int
Interval = Bc/CIR = 8000/100000 = 80 ms
Increment = Bc/8 = 8000/8 = 1000 bytes
Byte Limit = Increment + Be/8 = 1000 + 8000/8 = 2000 bytes

Reference:
http://www.cisco.com/warp/public/125/framerelay_ts_cmd.html

QUESTION NO: 5
Consider the following scenario: An interface has been configured for custom queuing across a DS3 interface. Bandwidth has been allocated for three application flows: A, B and C. The average packet for each application is as follows: Application A= 2000 Application B= 1000 Application C= 500
You wish to configure the router to allow for 20% of the bandwidth to be allocated to flow A, 50% for flow B, and the remaining 30% for flow C. If only one packet is serviced for flow A per pass, how many packets need to be allowed on flow C to maintain the
20:50:30
ratio?
A.
3
B.
4
C.
5
D.
6
E.
500
F.
More information needed
Answer: D
Explanation:
If flow A uses 20% of the bandwidth and flow C uses 30%, then C uses 1.5 times the bandwidth as A. The average byte size of A is 2000 bytes. 2000 times 1.5 is 3500 bytes. That would give the bandwidth of 3000 bytes for flow C. Since the average packet size of C is 500 bytes, 3000/500 = 6.

QUESTION NO: 6
Your VOIP network needs to give priority to the VOIP traffic across the serial interface of a router. You wish to support this by implementing a solution that enables the router to service the Voice traffic in a strict priority queue. All other non-voice traffic should be serviced using the weighted fair queuing mechanism. Which command should you enable on this serial interface?
A. fair-queue
B. ip cef
C. priority-group
D. ip rtp priority
E. priority-queuing
Answer: D
Explanation: The “ip rtp priority” command creates a strict priority queue for voice packets while providing WFQ for non-voice traffic. To reserve a strict priority queue for a set of Real-Time Transport Protocol (RTP) packet flows belonging to a range of User Datagram Protocol (UDP) destination ports, use the ip rtp priority command in interface configuration mode. This command is most useful for voice applications, or other applications that are delay-sensitive. This command extends and improves on the functionality offered by the ip rtp reserve command by allowing you to specify a range of UDP/RTP ports whose voice traffic is guaranteed strict priority service over any other queues or classes using the same output interface. Strict priority means that if packets exist in the priority queue, they are dequeued and sent first-that is, before packets in other queues are dequeued.
Incorrect Answers:
A. This command can be used for the default class (commonly known as the class-default class) only. You can use it in conjunction with either the queue-limit command or the random-detect command. The class-default class is the default class to which traffic is directed if that traffic does not satisfy the match criteria of other classes whose policy is defined in the policy map.
B. This will enable Cisco Express Forwarding, which will not fulfill the requirements of this question.
C. C, E. This will enable priority queuing, which could indeed be used to give RTP packets priority over other protocols, but used alone will not provide the mechanism for having the other traffic types serviced in a WFQ manner as described in this question. Reference:
http://www.ciscocom/en/US/products/sw/iosswrel/ps5207/products_command_reference_chapter09186a00801a

QUESTION NO: 7
A serial interface with flow-based WFQ is carrying 25 flows in the following fashion:
*
Twelve flows are marked as IP Precedence 0.
*
Ten flows are marked as IP Precedence 1.
*
Three flows are marked as IP Precedence 5.
Based on the above information, how much interface bandwidth is allocated to one of flows that are marked as IP Precedence 5?
A. 1%
B. 4%
C. 12%
D. 15%
E. 33%
F. Cannot tell from the information given
Answer: C
Explanation:
The total parts are found by adding one to each Precedence value, multiplying by the number of flows in that Precedence, and then totaling the parts (weights). Interface bandwidth is allocated to one of flows that are marked as IP Precedence is calculated as shown below.
(5+1) 6 6
———————————————-= ————= ——= 12%
[12*(0+1)]+ [10*(1+1)]+ [3*(5+1)] 12+20+18 50

Incorrect Answers:
B. If we took one flow and divided it by the number of total flows, the answer would be 4% (1/25). However, the correct answer is found using the formula above.

QUESTION NO: 8
Using the 3 layer hierarchical approach to a network, What QoS functions are performed at the access layer? (Choose 2)
A. Packet classification
B. Congestion management
C. Classification preservation.
D. Congestion avoidance
E. Admission control
Answer: A, E
Explanation:
As per Cisco’s Hierarchical network model, There are 3 network layers: The Core layer, The distribution layer, and the Access layer. The Core or backbone of the network should not be involved in Processor intensive tasks. Tasks such as packet classification and access control are limited to the access layer and in some cases to the distribution layer. It is the edge routers that classify the QoS traffic, as well as control the QoS admissions into the network. Incorrect Answers: B, D. These are functions of the distribution layer. It could be argued that certain aspects of congestion avoidance and management are handled by edge routers, options A and D are better choices.
C. Differentiated Services markings are marked at the access layer edge routers, but preserved throughout the network at the distribution and core layers.

QUESTION NO: 9 You need to give your new VOIP traffic priority over other traffic types in your network. To do this, you plan to implement custom queuing. What statement is FALSE about custom queuing?
A. Custom queuing defines up to 16 queues.
B. Custom queuing has one preemptive priority queue. This can be extended to multiple priority queues by configuring the ‘lowest-custom’ queue in the ‘queue-list’.
C. In custom queuing there is a weight assigned to each queue which specifies how each queue is treated.
D. With custom queuing you cannot specify a minimum bandwidth guarantee per queue.
E. In custom queuing you can classify based on the incoming interface.
Answer: B
Explanation:
With custom queuing there is no pre-emptive queue. Bandwidth is statically serviced based on the configuration, and the queue that is being serviced at any given time will finish before servicing the next queue.
Custom Queuing (CQ) With CQ, bandwidth is allocated proportionally for each different class of traffic. CQ allows you to specify the number of bytes or packets to be drawn from the queue, which is especially useful on slow interfaces
Why Use CQ? You can use the Cisco IOS QoS CQ feature to provide specific traffic guaranteed bandwidth at a potential congestion point, assuring the traffic a fixed portion of available bandwidth and leaving the remaining bandwidth to other traffic. For example, you could reserve half of the bandwidth for SNA data, allowing the remaining half to be used by other protocols. If a particular type of traffic is not using the bandwidth reserved for it, then unused bandwidth can be dynamically allocated to other traffic types. Restrictions CQ is statically configured and does not adapt to changing network conditions. With CQ enabled, the system takes longer to switch packets than FIFO because the packets are classified by the processor card.

QUESTION NO: 10
Which of the following is a required configuration parameter for setting up NBAR?

A. match protocol IP
B. match nbar type 1
C. match ftp session passive
D. match protocol http
E. match url www.cisco.com
Answer: D
Explanation: Configuring a Traffic Class
To configure a traffic class and the match criteria that will be used to identify traffic as belonging to that class, use the class-map global configuration command. To define the match criteria, use the following commands beginning in global configuration mode. In the following procedure, all traffic matching a specified protocol will be classified as belonging to the traffic class. The traffic class will classify traffic while the traffic policy configuration will determine how to treat the traffic. For instance, if you wanted all FTP traffic to be marked with the QoS group value of 1, you would use the match protocol ftp command in class-map configuration mode, and use the set qos-group 1 command in policy-map class configuration mode (assuming the traffic policy uses the specified class). Therefore, the classification purpose (classifying FTP traffic) would be handled in the traffic class, while the QoS feature (marking the QoS group value to 1) would be handled in the traffic policy.
Configuring a Traffic Class with NBAR Example
In the following example, the class-map class1 command uses the NBAR classification of SQL*Net as its matching criterion: Router(config)# class-map class1 Router(config-cmap)# match protocol sqlnet

QUESTION NO: 11 The Testking network is using Class of Service to prioritize the traffic throughout the network. Setting the CoS IP Precedence bits can be done in what situation?
A. For ATM CLP traffic only
B. To set the frame-relay DE bit
C. When we receive HDLC frame with DEADBEEF pattern
D. On a router on ISL or DOT1Q trunks in the output direction only
E. None of the above
F. All of the above
Answer: E
Explanation:
CoS refers to the ability of a network to provide differentiated service to selected network traffic over packet networks and cell networks. By default, the Cisco IOS software leaves the IP Precedence value untouched, preserving the precedence value set in the header, allowing all internal network devices to provide service based on the IP Precedence setting. This policy follows the standard approach stipulating that network traffic should be sorted into various types of service at the basic perimeter of the network and that those types of service should be implemented in the core of the network. Routers in the core of the network can then use the precedence bits, for example, to determine the order of transmission, the likelihood of packet drop, and so on. You can use any of the following features to set the IP precedence in packets:
1.
Policy-Based Routing
2.
QoS Policy Propagation via Border Gateway Protocol
3.
Committed Access Rate
Incorrect Answers:
A, B. The COS bit can be set for any FR/ATM traffic, using policy based routing. Frame relay and ATM networks can be configured to adjust traffic settings based on the Cell Loss Priority (CLP) and frame DE values, but the CoS bit is not limited to this type of traffic only.
C. The CoS bits can not be used based on layer 2 information in PPP and HDLC links, since specific identifiers are needed.
D. The CoS IP Precedence bits can be set based on both incoming and outgoing traffic.

QUESTION NO: 12 The Testking network plans to implement some method of quality of service using DSCP information. In comparing the different options which of the following statements is TRUE?
A. The IP precedence and DSCP have no overlapping fields.
B. The DSCP contains class selectors for backward compatibility with the IP precedence.
marketing naming convention.
D. The last 2 bit of the DSCP overlaps with the IP precedence.
Answer: A

Explanation:
DiffServ introduces the concept of the DiffServ Code Point (DSCP) that uses the first 6 bits of the TOS field thereby giving 26 = 64 different values. RFC 2474 describes the Differentiated Services (DS) field and the DiffServ Code Point (DSCP). A comparison of these two is displayed below:
As you can see from the comparison of the two packet formats, there are no overlapping fields.

QUESTION NO: 13 The TestKing network is using QoS to prioritize the critical traffic over busy links. What command would be used to configure Modular QoS CLI (MQC) to allow for a
there is no congestion, to allow the use of more bandwidth?
A. bandwidth 64
B. priority 64
C. police 64000 confirm-action transmit exceed-action drop
D. shape average 64000
E. all of the above
Answer: A
Explanation:
MQC is a framework that provides a clear separation between a classification policy and
the specification of other parameters that act on the results of that applied classification
policy.
Broadly, MQC is configured and implemented as follows:

1.
Define a traffic class with the class-map command.
2.
Create a service policy by associating the traffic class with one or more QoS features (using the policy-map command).
3.
Attach the service policy to the interface with the service-policy command.
To specify the bandwidth to be applied, configure the bandwidth as follows:
Router(config-pmap-c)# bandwidth Specifies a minimum bandwidth
{bandwidth-kbps percent percent} guarantee to a traffic class. A minimum
bandwidth guarantee can be specified in kilobits per second or by a
percentage of the overall available
bandwidth.
Incorrect Answers:
B. This is used to specify the priority of the traffic, but not the actual bandwidth to be used.
C. This command configures policing on the interface, so any traffic exceeding the 64 kbps will be dropped, even when there is no congestion.
D. This is used to specify the average traffic shaping, as specified by the CIR.
Reference:
http://www.cisco.com/en/US/products/sw/iosswrel/ps5014/products_feature_guide_chapter09186a008008813a

QUESTION NO: 14 Priority queuing is being configured on router TK1 to give mission critical traffic priority over the WAN link. What statement is true with regard to priority queuing?
A. There are 4 priority queues: high, medium, normal, low.
B. The high and medium queues have precedence over the default queue.
C. The classification is configurable with the ‘priority-list’ command
D. The default queue is the normal queue, by default.
E. All of the above. Leading the way in IT testing and certification tools, www.testking.com
– 289 –
F. None of the above.

Answer: E
Explanation:
There are four priority queues: high, medium, normal, and low- listed in order from
highest to lowest priority.
The default queue is the normal queue. Traffic that is not explicitly defined in the priority
list will be assigned this priority by default.
Priority queuing is configured using the “priority-list” command.
Example:
In the following example, queuing priority for all telnet and SMTP traffic is assigned the
high priority.
priority-list 1 protocol ip high tcp 23
priority-list 1 protocol ip high tcp 25

QUESTION NO: 15
The IP precedence of a packet can be determine from:

A. All 8 bits of the ToS byte
B. Bits 3, 4 and 6 of the ToS byte.
C. The three most significant bits of the ToS byte.
D. The three least significant bits of the ToS byte.
Answer: C
Explanation:
This DSCP field definition allows for up to 64 distinct values (levels of service), 0 through 63, of classification on IP frames. The last two bits represent the Early Congestion Notification (ECN) bits. IP Precedence is only the 3 most significant bits of the ToS field. As a result, IP Precedence maps to DSCP by using IP Precedence as the 3 high-order bits and padding the lower-order bits with 0.

QUESTION NO: 16
Part of the configuration file of router TK1 is shown in the diagram below:

Based upon the MQC configuration shown in the exhibit, what statement is correct?
A. ip cef must be disabled (using no ip cef) in order for the NBAR classification (match protocol) commands to function.
B. All non-FTP and non-TFTP incoming traffic to the fa0/0 interface will be classified into the class-default traffic class and marked as DSCP 0.
C. All incoming traffic to the fa0/0 interface will be classified into the class-default traffic class and no DSCP marking will be performed.
D. Either FTP or TFTP incoming traffic to the fa0/0 interface willb e marked as af11.
E. None of the above.
Answer: C
Explanation:
Based on the configuration above, the service policy named mark will be applied to all traffic incoming on the fast ethernet 0/0 interface. In the policy map, all matching traffic will be assigned the Differentiated Services Code Point of assured forwarding 11. In this case, only traffic that is both FTP and TFTP will match the class-match due to the “match-all” keyword. Since a packet can not be both TFTP and FTP, no traffic will match and the default action will be taken.
Incorrect Answers:
D: This would be true if the “match-any” keyword was used in the “bulk” policy, but in this example the traffic must be both FTP and TFTP, which is not possible.

QUESTION NO: 17
The relevant part of a TestKing router’s configuration is displayed below:
Classed-Based marking has been configured as shown above to sort traffic into classes for
appropriate treatment by upstream routers. Unfortunately, traffic received by an upstream

marked *EF* and packets previously set by end-users as CS3 and EF are not remarked to DSCP 00000. Which of the following issues could be the cause of the problem? (Select two).
A. Using NBAR to classify RTP traffic requires that IP CEF be disabled.
C. The router has been improperly configured to only mark traffic flowing in the wrong direction.
D. The set ip dscp default command does not mark the packet with dscp 0000, but instead resets the command use back to Cisco IOS default settings.
E. The Class-map VoIP-Remark has been improperly configured to simultaneously match more than one traffic type.
Answer: C, E
Explanation:
The first problem is that the service policy named Policy-NoTrust is being applied to the input direction of the ethernet interface, when it should be applied in the outbound direction for the upstream routers to see the correct DSCP markings of the packets. The second problem is the fact that the keyword “match-all” is being applied to the VOIP-Remark class map. This keyword instructs the IOS that all of the criteria in the entire map must match in order to be applied. In the configuration above, only a packet that matches all three of the criteria (DSCP EF, DSCP CS3, and DSCP AF21) will be marked, instead of packets that match any one of those. In this example, the correct syntax should have been “class-map match-any VoIP-Remark”

QUESTION NO: 18
Router TK1 is configured for QoS as shown below: Based on the configuration displayed in the exhibit, what statement is correct about ingress traffic to the fa0/0 interface on TK1?
A. All ingress frames marked as COS 0 will be marked as DSCP 0.
B. All ingress frames marked as COS 1 will be marked as DSCP cs1.
C. All ingress HTTP traffic will be marked as DSCP af21.
D. All ingress Napster traffic will be marked as DSCP cs1.
E. All ingress frames marked as COS 3 or COS 4 will be marked as DSCP af33.
F. None of the above.
Answer: E
Explanation:
Since the “match cos 3 4” statement lies within a single configuration line, only one or the
other need to match. When the keyword “match-all” is used, all distinct lines must match
for the rule to take effect. Since the values shown in choice E are displayed in a single
line, all traffic with COS values of 3 or 4 will match, and will subsequently be forwarded
after being marked as AF33.

Additional info:
To access the QoS class map configuration mode to configure QoS class maps, use the
class-map command. Use the no form of this command to delete a class map.
class-map name [match-all match-any]
no class-map name [match-all match-any]
Syntax Description

name Class map name.
match-all (Optional) Matches all match criteria in the class map.
match-any (Optional) Matches one or more match criteria.
Defaults
When you do not specify the match-all or match-any keyword, the default is match-all.

Incorrect Answers:

A. CoS values of 0 are not automatically marked with a DSCP value of 0 B, D. Here, only frames marked as COS and using the Napster protocol will be marked with a DSCP value of 1.
C. Only traffic that is both HTTP and Telnet will be marked as such. This is obviously not possible since HTTP uses port 80 while telnet uses port 23.
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