Exam 300-620 topic 1 question 12 discussion

Actual exam question from Cisco's 300-620

Question #: 12
Topic #: 1

An engineer is implementing Cisco ACI at a large platform-as-a-service provider using APIC controllers, 9396PX leaf switches, and 9336PQ spine switches. The leaf switch ports are configured as IEEE 802.1p ports. Where does the traffic exit from the EPG in IEEE 802.1p mode in this configuration?

A. from leaf ports tagged as VLAN 0
B. from leaf ports untagged
C. from leaf ports tagged as VLAN 4094
D. from leaf ports tagged as VLAN 1

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Suggested Answer: A 🗳️

by Irgond07 at Jan. 31, 2021, 8:56 p.m.

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Irgond07

Highly Voted 4 years, 4 months ago

A is correct option. FYI... Trunk (Tagged - classic IEEE 802.1q trunk)—Traffic for the EPG is sourced by the leaf switch with the specified VLAN tag. The leaf switch also expects to receive traffic tagged with that VLAN to be able to associate it with the EPG. Traffic received untagged is discarded. • Access (Untagged)—Traffic for the EPG is sourced by the leaf as untagged. Traffic received by the leaf switch as untagged or with the tag specified during the static binding configuration is associated with the EPG. • Access (802.1p)—If only one EPG is bound to that interface, the behavior is identical as in the untagged case. If other EPGs are associated with the same interface, traffic for the EPG is sourced with an IEEE 802.1q tag using VLAN 0 (IEEE 802.1p tag), or is sourced as untagged in the case of EX switches.

upvoted 6 times

alphatest

3 years ago

With first generation switches, it can be UNTAGGED if there's only one EPG associated to the port, or VLAN0 when there are more. The question is ambiguous

upvoted 1 times

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designated

Most Recent 7 months, 1 week ago

Selected Answer: A

A is correct

upvoted 1 times

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jmaroto

3 years ago

● Access (IEEE 802.1p) or native: With Cisco Nexus 9300-EX and later switches, this option is equivalent to the Access (untagged) option. This option exists because of first generation leaf switches. On Cisco Nexus 9300-EX or later switches, you can assign the native VLAN to a port either by using the Access (untagged) option or the Access (IEEE 802.1p) option. However, we recommend that you use the Access (untagged) option because the Access (IEEE 802.1p) option was implemented specifically to address https://www.cisco.com/c/en/us/td/docs/dcn/whitepapers/cisco-application-centric-infrastructure-design-guide.html#_Toc6452851 The question reference fisrt generation leaf and spine switches, this is the key

upvoted 1 times

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MaxG

3 years, 11 months ago

A is correct. The VLAN 0 Priority Tagging feature enables 802.1Q Ethernet frames to be transmitted with the VLAN ID set to zero. These frames are called priority tagged frames. Setting the VLAN ID tag to zero allows the VLAN ID tag to be ignored and the Ethernet frame to be processed according to the priority configured in the 802.1P bits of the 802.1Q Ethernet frame header. https://www.cisco.com/c/en/us/td/docs/switches/connectedgrid/cg-switch-sw-master/software/configuration/guide/vlan0/b_vlan_0.html

upvoted 4 times

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