ACSP - Aruba Certified Switching Professional VLANs and Link Aggregation Questions and Answers

Question 1

A network administrator is configuring a link aggregation group (LAG) between two ArubaOS-CX switches. The administrator wants to ensure that the LAG is formed only if LACP negotiations are successful between the two switches. Which LACP mode combination should be configured on the two switches to achieve this?

Accepted Answer

Active on one switch and Passive on the other switch.

Answer

For a dynamic LACP LAG to form, at least one side must be in 'active' mode to initiate the LACP negotiation. An active-passive combination is a standard and valid configuration where the active side sends LACPDU packets, and the passive side responds, successfully forming the aggregation. Two passive sides will never form a LAG because neither will initiate the negotiation.

Question 2

An engineer is setting up a new access switch that connects to a distribution switch using two bundled links. The distribution switch is configured for a dynamic LACP LAG. The new access switch is unconfigured (factory default). To allow the access switch to boot up, obtain a DHCP address, and download its configuration via Zero-Touch Provisioning (ZTP), what feature must be enabled on the distribution switch's LAG interface?

Accepted Answer

LACP fallback-static

Answer

LACP fallback-static is designed for scenarios like ZTP or PXE booting. When the distribution switch does not receive LACP PDUs from the downstream device (like a factory-default switch), LACP fallback-static allows one port of the LAG to come up as a normal, non-bonded interface. This enables the new switch to communicate on the network to get its configuration.

Question 3

A network administrator configures a Layer 2 LAG between two ArubaOS-CX switches to carry traffic for multiple VLANs. Which command is used on the logical LAG interface to specify which VLANs are permitted to cross the aggregated link?

Accepted Answer

vlan trunk allowed <vlan-list>

Answer

On ArubaOS-CX switches, when an interface (including a logical LAG interface) is configured as a trunk to carry multiple VLANs, the `vlan trunk allowed` command is used to define the specific list of VLANs that are permitted to traverse that trunk.

Question 4

Which of the following is a primary advantage of using dynamic LACP over a static link aggregation group (LAG)?

Accepted Answer

It provides active detection of link failures and misconfigurations.

Answer

Dynamic LACP uses Link Aggregation Control Protocol Data Units (LACPDUs) to actively communicate between peer switches. This allows it to detect misconfigurations (like a mismatched cable) or unidirectional link failures that a static LAG cannot, as static LAGs do not exchange any control information.

Question 5

An ArubaOS-CX switch has a two-port LAG configured. An administrator wants to understand how traffic is being distributed across the member links. By default, what information does an ArubaOS-CX switch use in its hashing algorithm for link aggregation load balancing?

Accepted Answer

Source and Destination IP addresses.

Answer

In ArubaOS-CX, the default hashing algorithm for load balancing traffic across the member ports of a LAG uses the Layer 3 source and destination IP addresses of the packets. While other parameters can be configured, this is the default behavior.

(ACSP) Aruba Certified Switching Professional Practice Test

(ACSP) Aruba Certified Switching Professional Practice Test

ACSP - Aruba Certified Switching Professional VLANs and Link Aggregation Questions and Answers