Implementing and Operating Cisco Service Provider Network Core Technologies (SPCOR) — Question 225

An engineer must apply an 802.1ad-compliant configuration to a new switchport with these requirements:
✑ The switchport must tag all traffic when it enters the port.
✑ The switchport is expected to provide the same level of service to traffic from any customer VLAN.
Which configuration must the engineer use?

Answer options

• A. interface GigabitEthernet1/0/1 switchport mode trunk switchport trunk encapsulation dot1q encapsulation ISL bridge-domain 12
• B. interface GigabitEthernet1/0/1 ethernet dot1ad uni c-port service instance 12 encapsulation dot1q rewrite ingress tag push dot1ad 21 symmetric bridge-domain 12
• C. interface GigabitEthernet1/0/1 ethernet dot1ad uni s-port service instance 12 encapsulation default rewrite ingress tag push dot1ad 21 symmetric bridge-domain 12
• D. interface GigabitEthernet1/0/1 ethernet dot1ad nni service instance 12 encapsulation dot1ad bridge-domain 12

Correct answer: C

Explanation

The correct answer, C, uses the 'uni s-port' configuration which is suitable for tagging all incoming traffic for service instances, ensuring compliance with the 802.1ad standard. Option A is incorrect because it uses a trunk configuration that does not specifically meet the tagging requirement for customer VLANs. Option B is incorrect as it specifies 'uni c-port', which does not apply to the service instance tagging needed. Option D is also wrong since it uses 'nni' which is intended for network-to-network interfaces, not for customer traffic tagging.