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QUESTION 11
Refer to the Cisco IOS XR policy-map configuration exhibit. What is wrong with the policy-map configuration?
A. missing the priority percent command under class one and class two
B. missing the police command under class one and class two
C. missing the police command under class three
D. missing the priority bandwidth command under class one and class two
E. missing the bandwidth command under class one and class two
Answer: B
Explanation:
Hierarchical policing is also supported. In such a configuration, both parent and child policies have class-maps
containing policing statements, as in the following example:
!
policy-map child
class gold
police rate percent 50 conform-action set precedence immediate exceed-action drop
!
!
policy-map parent
class match_all
police rate 10000 kbps burst 15000 exceed-action drop service-policy child
QUESTION 12
When configuring class-based WRED on Cisco routers, which WRED parameter is not user configurable on a Cisco IOS XR but is user configurable on a Cisco IOS and IOS XE?
A. the ingress or egress direction where the class-based WRED policy will be applied
B. the maximum threshold
C. the minimum threshold
D. the mark probability denominator
Answer: D
QUESTION 13
Which of the following three statements are correct regarding IPv6 QoS? (Choose three.)
A. The traffic class field in the IPv6 header can be used to set specific precedence or DSCP values.
B. A 20-bit flow label field enables per-flow processing.
C. DS-TE is not supported by IPv6.
D. Per-hop behavior in IPv6 networks is based on EXP bits.
E. IPv6 QoS features are configured using the modular QoS CLI on Cisco routers.
Answer: ABE
QUESTION 14
With unmanaged CE routers, at which point in the service provider network is the QoS trust boundary, and what is required at the trust boundary?
A. between the CE and PE router and mapping of the customer traffic classes into the service provider
traffic classes at the PE router ingress
B. between the CE and PE router and trusting the QoS markings from the CE router and applying the
required QoS mechanisms based on the customer QoS markings
C. between the PE and the P router and mapping of the customer traffic classes into the service provider
traffic classes at the P router ingress
D. between the PE and P router and trusting the QoS markings from the CE router and applying the required
QoS mechanisms based on the customer QoS markings
E. between the customer network and the CE router ingress and applying the required egress QoS policy
on the CE router
Answer: A
QUESTION 15
On the Cisco IOS XR, when using the match protocol command within a class-map to classify traffic, you noticed that the match protocol option on the Cisco IOS XR shows much fewer protocol options than on the Cisco IOS or IOS XE, like there is no option such as the match protocol yahoo-messenger command on the Cisco IOS XR. Why is this?
A. because the Cisco IOS XR router does not have the correct software packages installed
B. because when defining the class-map, the class-map type should be set to type inspect: class-map
type inspect class-map-name command
C. because NBAR is not supported on the Cisco IOS XR
D. because flexible packet matching has not been enabled on the Cisco IOS XR router
Answer: C
QUESTION 16
Within the service provider core network, which two QoS mechanisms are typically deployed on the P routers? (Choose two.)
A. LLQ
B. traffic policing and remarking
C. WRED
D. traffic shaping
E. traffic classification and markings
F. link fragmentation and interleaving
Answer: AC
QUESTION 17
Which three steps are required to configure QPPB on Cisco IOS XR routers? (Choose three.)
A. Apply a QPPB route policy to the BGP process using the table-policy command
B. Apply a QPPB route policy to the BGP neighbor using the route-policy command
C. Define a QPPB route policy to match the customer routes, then set the IP precedence or qos- group
D. Define a QPPB route policy to match the customer IP precedence or qos-group markings, then set the
BGP community
E. Enable QPPB on an interface using the ipv4 bgp policy propagation input ip-precedence|qos-group
destination|source command
F. Enable QPPB on an interface using the ipv4 bgp policy propagation output ip-precedence|qos- group
destination|source command
Answer: ACE
Explanation:
QoS Policy Propagation via BGP (QPPB), is a mechanism that allows propagation of quality of service (QoS) policy and classification by the sending party based on access lists, community lists and autonomous system paths in the Border Gateway Protocol (BGP), thus helping to classify based on destination instead of source address.
QUESTION 18
The Cisco IOS and IOS XE qos pre-classify command allows which kind of packet classification on IP packets that are encapsulated with GRE and IPsec?
A. allows for packets to be classified based on the ToS byte values before packet encryption
B. allows for packets to be classified based on the ToS byte values after packet encryption
C. allows for packets to be classified based on the packet payload before packet encryption
D. allows for packets to be classified based on the packet payload after packet encryption
E. allows for packets to be classified based on the packet header parameters other than the ToS byte
values after packet encryption
Answer: A
Explanation:
http://www.cisco.com/en/US/tech/tk543/tk545/technologies_tech_note09186a008017405e.shtml
The qos pre-classify command
When packets are encapsulated by tunnel or encryption headers, QoS features are unable to examine the original packet headers and correctly classify the packets. Packets traveling across the same tunnel have the same tunnel headers, so the packets are treated identically if the physical interface is congested. With the introduction of the Quality of Service for Virtual Private Networks (VPNs) feature, packets can now be classified before tunneling and encryption occur.
In this example, tunnel0 is the tunnel name. The qos pre-classify command enables the QoS for VPNs feature on tunnel0:
Router(config)# interface tunnel0
Router(config-if)# qos pre-classify
QUESTION 19
Which are typical class-based marking policies that are implemented on service provider IP NGN PE routers?
A. On the PE ingress, classify the customer traffic and then mark with qos-group. On the PE egress,
classify based on the qos-group and then mark with mpls exp.
B. On the PE ingress, classify the customer traffic and then mark with mpls exp. On the PE egress,
classify based on the mpls exp and then mark with qos-group.
C. On the PE ingress, trust the customer QoS markings. On the PE egress, classify based on the
customer QoS markings and then mark with qos-group.
D. On the PE ingress, trust the customer QoS markings. On the PE egress, classify based on the
customer QoS markings and then mark with mpls exp.
Answer: A
QUESTION 20
Which item is not available to be used for QoS classification in Cisco IOS XR?
A. MAC SA
B. protocol
C. inner EXP
D. discard-class
E. QoS-group
F. VLAN
Answer: C
QUESTION 21
Which statement is correct regarding the default MPLS TTL behavior?
A. When an ingress edge LSR receives an IP packet, it will decrement the IP TTL field by 1; then it will
set the MPLS Label TTL field to 255.
B. When an ingress edge LSR receives an IP packet, it will decrement the IP TTL field by 1; then it will
copy the decremented IP TTL field into the MPLS Label TTL field.
C. When an ingress edge LSR receives an IP packet, it will just copy the IP TTL field into the MPLS Label
TTL field.
D. When an ingress edge LSR receives an IP packet, it will copy the IP TTL field into the MPLS Label
TTL field first; then it will only decrement the MPLS Label TTL field by 1.
E. When an ingress edge LSR receives an IP packet, it will copy the IP TTL field into the MPLS Label
TTL field first; then it will only decrement the IP TTL field by 1.
Answer: B
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