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300-415 · Question #377

Refer to the exhibit. An engineer is configuring a QoS policy to shape traffic for VLAN 100 on a subinterface. Which policy configuration accomplishes the task?

The correct answer is A. policy-map shape_GigabitEthernet4.100 class class Queue0 service-policy xyz_QoS-model shape average 100000000 ! interface GigabitEthernet4.100 encapsulation dot1Q 100 service-policy output shape_GigabitEthernet4.100. To shape traffic on a specific subinterface for a VLAN, the policy-map applied to the subinterface must be correctly named and explicitly applied to the corresponding subinterface, with the encapsulation dot1Q matching the target VLAN.

Policies

Question

Refer to the exhibit. An engineer is configuring a QoS policy to shape traffic for VLAN 100 on a subinterface. Which policy configuration accomplishes the task?

Options

  • Apolicy-map shape_GigabitEthernet4.100 class class Queue0 service-policy xyz_QoS-model shape average 100000000 ! interface GigabitEthernet4.100 encapsulation dot1Q 100 service-policy output shape_GigabitEthernet4.100
  • Bpolicy-map shape_GigabitEthernet4.200 class class-default service-policy xyz_QoS-model shape average 100000000 ! interface GigabitEthernet4.100 encapsulation dot1Q 100 service-policy output shape_GigabitEthernet4.200
  • Cpolicy-map shape_GigabitEthernet4.100 class class-default service-policy xyz_QoS-model shape average 100000000 ! interface GigabitEthernet4.100 encapsulation dot1Q 200 service-policy output shape_GigabitEthernet4.100
  • Dpolicy-map shape_GigabitEthernet4.200 class class Queue0 service-policy xyz_QoS-model shape average 100000000 ! interface GigabitEthernet4.100 encapsulation dot1Q 100 service-policy output shape_GigabitEthernet4.100

How the community answered

(42 responses)
  • A
    69% (29)
  • B
    10% (4)
  • C
    19% (8)
  • D
    2% (1)

Why each option

To shape traffic on a specific subinterface for a VLAN, the policy-map applied to the subinterface must be correctly named and explicitly applied to the corresponding subinterface, with the `encapsulation dot1Q` matching the target VLAN.

Apolicy-map shape_GigabitEthernet4.100 class class Queue0 service-policy xyz_QoS-model shape average 100000000 ! interface GigabitEthernet4.100 encapsulation dot1Q 100 service-policy output shape_GigabitEthernet4.100Correct

This configuration correctly associates the policy-map `shape_GigabitEthernet4.100` with the `interface GigabitEthernet4.100`, which is configured for `encapsulation dot1Q 100`. The `service-policy output shape_GigabitEthernet4.100` command applies the shaping policy to the correct subinterface, ensuring traffic for VLAN 100 is shaped.

Bpolicy-map shape_GigabitEthernet4.200 class class-default service-policy xyz_QoS-model shape average 100000000 ! interface GigabitEthernet4.100 encapsulation dot1Q 100 service-policy output shape_GigabitEthernet4.200

This option defines a policy-map named `shape_GigabitEthernet4.200` but applies it to `interface GigabitEthernet4.100`, creating a mismatch between the policy name and its application.

Cpolicy-map shape_GigabitEthernet4.100 class class-default service-policy xyz_QoS-model shape average 100000000 ! interface GigabitEthernet4.100 encapsulation dot1Q 200 service-policy output shape_GigabitEthernet4.100

This option configures `encapsulation dot1Q 200` on `interface GigabitEthernet4.100`, which does not match the requirement to shape traffic for VLAN 100.

Dpolicy-map shape_GigabitEthernet4.200 class class Queue0 service-policy xyz_QoS-model shape average 100000000 ! interface GigabitEthernet4.100 encapsulation dot1Q 100 service-policy output shape_GigabitEthernet4.100

This option defines a policy-map named `shape_GigabitEthernet4.200` but applies `service-policy output shape_GigabitEthernet4.100`, creating a naming mismatch between the defined policy and the applied policy.

Concept tested: IOS XE QoS policy-map application on subinterfaces

Source: https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/qos_plcshp/configuration/xe-3s/qos-plcshp-xe-3s-book/qos-plcshp-overview.html

Topics

#QoS#Traffic Shaping#Policy Map#Subinterface Configuration

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