HPE7-A08 Exam Dumps - HP Aruba Certified Switching Expert Questions and Answers

In a high-security " Colorless Ports " environment using AOS-CX, we often run both 802.1X (Dot1x) and MAC Authentication (MAC-auth) on the same port to handle a mix of corporate laptops and " dumb " IoT devices (printers, cameras).

The Default Behavior: By default, the switch usually attempts 802.1X first. When a device like a printer is plugged in, it does not have an 802.1X " supplicant " to respond to the switch ' s EAPOL-Request packets. The switch will wait for a series of timeouts and retries (EAPOL timeouts) before it gives up on 802.1X and moves on to the next method (MAC-auth). This waiting period is what causes the " few minutes " delay the user is experiencing.

Auth-Precedence vs. Auth-Priority:

Auth-Precedence: This defines the order in which the switch attempts the authentication methods.

Auth-Priority: This defines which method " wins " if multiple methods succeed (relevant for a PC that might trigger both).

The Solution: By changing the auth-precedence to mac-auth dot1x, the switch immediately captures the device ' s MAC address and sends it to the RADIUS server (like Aruba ClearPass) for authentication.

For a printer, MAC-auth succeeds immediately, and the port is authorized without waiting for 802.1X timeouts.

For a corporate laptop, MAC-auth happens first (granting basic or initial access), and then the 802.1X process can trigger immediately after to provide higher-level " User " access.

Why other options are incorrect:

Option A: Disabling 802.1X removes the security for corporate devices on those ports; it is not a " secure configuration " maintenance.

Option B: Increasing the timeout would make the delay worse , not better.

Option D: There is no specific " MAC auth start value " timer in AOS-CX that would solve a multi-minute delay caused by the 802.1X failure wait.

CLI Example:

Bash

interface 1/1/1

aaa authentication port-access auth-precedence mac-auth dot1x

When configuring a Multi-Chassis Link Aggregation Group (MC-LAG) in a VSX environment, the two physical switches must act as a single logical entity to the connected device (the Gateway).

The Concept of Multi-Chassis (Option A): In many networking architectures, including Aruba ' s legacy AOS-Switch and the conceptual models taught in certification, a LAG must be explicitly identified as " Multi-Chassis " to enable the coordination between the two physical switches. In AOS-CX , while you don ' t literally type " multi-chassis " on the interface, the term is used in exam contexts to describe the MC-LAG functionality .

The " One Link Up " Problem: If the Gateway only sees one link up, it means the LACP negotiation has failed on one of the two switches. This happens because the two switches are not presenting the same LACP System ID to the Gateway. Without the proper multi-chassis/VSX coordination, Switch 1 and Switch 2 appear as two completely different devices. The Gateway’s LACP process will see two different IDs for what it thinks should be one bundle and will block one of the links to prevent a loop.

Why not B? vsx-sync is used to synchronize the commands between the two switches so you don ' t have to type them twice. While helpful for management, its absence doesn ' t prevent a link from coming up as long as you manually configured both sides identically.

Why not C? lacp mode active on the switch will work perfectly with either active or passive on the Gateway side.

The exhibit illustrates a high-availability design involving an AOS-CX 8325 VSX core pair and an AOS-CX 6300M VSF access stack. To determine the necessary change, we must evaluate the bandwidth relationship between the Inter-Switch Link (ISL) and the Access Uplinks .

VSX ISL Bandwidth Best Practice: A fundamental rule in Aruba VSX design is that the ISL (Inter-Switch Link) bandwidth should be equal to or greater than the bandwidth of the highest-speed uplink or the aggregate bandwidth of the downstream access connections. This ensures that in the event of a link failure (where traffic must traverse the ISL to reach its destination), the ISL does not become a bottleneck, causing packet loss or increased latency.

Analyzing the Current Topology:

The Access Uplinks from the CX 6300 stack to the CX 8325 core are utilizing 25GBase-SR (25 Gbps) connections.

The VSX ISL (ports 1/1/47 and 1/1/48 on the CX 8325s) is currently configured with 10GBase-SR (10 Gbps) optics.

This creates a " bottleneck " scenario where the core synchronization and failover path (10G) is significantly slower than the access path (25G).

Hardware Capabilities:

The AOS-CX 8325-48Y8C features 48 ports that support SFP/SFP+/SFP28 (1G/10G/25G).

Ports 1/1/47 and 1/1/48 are SFP28 capable. To adhere to best practices and match the 25G speed of the downstream 6300 uplinks, these ISL ports must be upgraded from 10G (SFP+) to 25G (SFP28) .

Evaluating Other Options:

Option B is incorrect because the CX 8325 does not support SFP56 (50G) transceivers; SFP56 is typically found on the CX 6300/6400 series.

Option C is incorrect because the CX 6300M does not have QSFP28 (100G) ports; it uses SFP56 for its high-speed uplinks.

Option D is incorrect because the 6300 is already using 25G. While it could support SFP56, upgrading the access side to 50G while leaving the Core ISL at 10G would only exacerbate the bandwidth mismatch.

Therefore, the most critical architectural correction is upgrading the 8325 ISL ports to SFP28 to ensure the ISL bandwidth matches the 25G access uplinks.

To resolve this QoS mapping issue on AOS-CX , you must understand the hierarchy of Trust Levels and how they interact with Link Aggregation Groups (LAGs) .

Trust Hierarchy: AOS-CX switches use a " top-down " approach for QoS.

Global Trust: Setting qos trust dscp globally means that, by default, every port on the switch will look at the Layer 3 DSCP markings to determine queue priority.

Interface Override: You can override the global setting on a per-interface basis. If a specific device or service (like the video streaming service in this prompt) relies solely on Layer 2 CoS (802.1p) markings rather than DSCP, the switch will ignore those CoS markings under the global DSCP policy and place the traffic in a default (best-effort) queue.

LAG Configuration Logic: In the AOS-CX architecture, a LAG is a logical interface (interface lag 20).

Configuration parameters for the bundle (such as VLANs, ACLs, and QoS trust) should be applied to the logical LAG interface , not the individual physical member ports (1/1/20 and 2/1/20).

Once applied to the LAG, the settings are automatically inherited by all physical members.

Analyzing the Options:

Option D (Correct): By entering the interface lag 20 context and applying qos trust cos, you are instructing the switch to ignore the global DSCP setting for this specific bundle and instead trust the Layer 2 priority bits. This allows the video service to once again map correctly to the intended priority queues.

Option A: This is unnecessarily complex. Setting the physical member ports to qos trust none and then the LAG to cos is redundant because the LAG configuration overrides the physical port settings in this context.

Option B: qos trust dscp, cos is not a valid AOS-CX command. Unlike the older AOS-S (ProCurve) software which allowed a combined dscp-cos trust, AOS-CX requires you to choose a single trust type (DSCP, CoS, or None) per interface.

Option C: This applies the configuration to the physical ports only. In an AOS-CX VSF/LAG environment, this is considered a configuration error or " best practice " violation, as the logical LAG interface should hold the configuration.

Device Profiles on AOS-CX switches are a " Lite " version of Dynamic Segmentation, allowing the switch to automatically configure a port when a specific device is detected via LLDP or CDP, without needing a RADIUS server.

Associate an LLDP group (Option C): To " catch " a device, you first define a Device Group (often an lldp-group) that contains match criteria such as the System Name or OUI of an Aruba AP. This group tells the switch which devices should trigger the profile.

Associate a role (Option A): Once a device matches the group, the switch needs to know what to do with it. The Role is the container that holds all the port attributes (VLAN, PoE priority, STP settings, etc.). The Device Profile ' s job is to " bridge " the group and the role together using the associate role and associate lldp-group commands.

Why other options are incorrect:

Options B, D, and E: These are all settings that are configured inside the Role . You do not associate a VLAN or an ACL directly to the Profile; you associate them to the Role, and then associate the Role to the Profile.

To answer this correctly, it is vital to distinguish between VSF (Virtual Switching Framework) and VSX (Virtual Switching Extension) .

VSF (Virtual Switching Framework) Logic: The CX 6200 and 6300 series use VSF to form a " stack. " In a VSF stack, multiple physical switches operate as a single logical device with a single control plane and a single configuration file.

LAG Configuration in VSF: Because a VSF stack is a single logical entity, creating a Link Aggregation Group (LAG) that spans multiple members is handled exactly like a standard LAG on a single switch. You simply create the interface lag X and then assign physical ports from different members (e.g., member 1 and member 2) to that same LAG ID.

The " multi-chassis " Keyword: The keyword multi-chassis (seen in Options B and D) is specific to VSX , which is used on high-end switches like the CX 6400 and 8000 series. VSX involves two separate control planes that synchronize information. In VSX, you must use the multi-chassis command to let the switches know the LAG is split across two different chassis. In VSF, this keyword is not used and would result in a syntax error on a 6200 switch.

Analyzing the Options:

Option A (Correct): It uses standard interface lag 1 syntax. It assigns port 1/1/1 (from member 1) and port 2/1/1 (from member 2) to the same LAG. This perfectly fulfills the requirement for redundant ports from both switches in a VSF stack.

Option B: Incorrect because it uses the multi-chassis keyword (VSX only).

Option C: Incorrect because it only configures a port from one switch (1/1/1), failing the requirement for redundancy across both switches.

Option D: Incorrect because it uses the multi-chassis keyword (VSX only).

Key Takeaway for the ACP-S Exam: * VSF (6200/6300) = Standard LAG configuration across members.

VSX (6400/8000) = Requires multi-chassis keyword under the LAG interface.

POST: Create a new object instance.

PUT: Modify a group of object properties.

PATCH: Modify object instance properties.

DELETE: Remove an object instance.

GET: Retrieve object instance properties.

AOS-CX is built with a REST-first architecture, where the Web UI and CLI both interact with the same internal database via an API. Understanding these standard HTTP methods is essential for network automation.

POST (Create): Used to create a new resource. For example, creating a new VLAN entry in the database.

GET (Read/Retrieve): Used to fetch information about a resource. It is a " read-only " operation used to check the status of a port or the contents of the routing table.

PUT (Replace/Modify Group): In the Aruba API context, PUT is used for a " complete update. " It essentially replaces the current object with a new set of properties. If you omit properties in a PUT request, they may return to default values.

PATCH (Partial Update/Modify Instance): PATCH is used for incremental changes. It allows you to modify only a specific subset of an object ' s properties (like changing only the description of a port) without having to resend the entire object configuration.

DELETE (Remove): Used to remove a specific resource instance from the switch database (e.g., deleting a VLAN or a static route).

The Local Priority (LP) applied to an incoming packet marked with DSCP 46 and CoS 7 depends on the configured QoS mapping.

DSCP 46 corresponds to Expedited Forwarding (EF), which is typically mapped to the highest priority.

CoS 7 also indicates high priority.

According to the QoS policy shown, the LP assigned is 1, indicating the highest priority level.

To influence BGP path selection, you must understand the BGP Best Path Selection Algorithm used by AOS-CX. When multiple paths to the same prefix exist, the switch evaluates attributes in a specific order.

The Decision Order:

Highest Weight (Proprietary/Local to the switch).

Highest Local Preference (Standard, used within an AS).

Locally originated.

Shortest AS Path .

Lowest MED (Metric) .

Local Preference (LP): Although Local Preference is an attribute that is typically passed between iBGP peers, it is the most common tool used on an ingress (import) policy from an eBGP peer to tell the local switch (and the rest of the AS) " this is our preferred exit/entry point. "

The default Local Preference is 100 .

By creating a route-map that sets the Local Preference to 200 and applying it to Peer A on import , the switch will see Peer A ' s route as having a higher LP than Peer B ' s route (which remains at 100).

Local Preference vs. Metric (MED): Local Preference is evaluated before the Metric (MED) in the decision process.

Option C works because LP 200 is higher than 100.

Option B is incorrect because setting a higher Metric (200) actually makes a route less preferred (lower metric wins).

Option D would technically make Peer A preferred (because Peer B would have a higher/worse metric), but because Local Preference is higher in the decision-making hierarchy, Option C is the more robust and standard BGP engineering choice in Aruba architectures.

Example CLI Logic:

Bash

route-map PREFER_A permit seq 10

set local-preference 200

!

router bgp 65001

neighbor < Peer_A_IP > route-map PREFER_A in

In an AOS-CX Virtual Switching Extension (VSX) environment, the Configuration Synchronization (vsx-sync) feature simplifies management by allowing the Primary switch to automatically push configuration settings to the Secondary switch.

Primary-Only Configuration: A fundamental rule of vsx-sync is that all synchronization commands must be configured on the Primary VSX node . The Secondary node simply receives and applies the configuration; it does not initiate the sync.

The time Synchronization Module: In AOS-CX, the command used to synchronize all time-related parameters—including NTP servers , authentication keys, and time zone settings—is vsx-sync time.

Command Logic: By adding vsx-sync time under the vsx context on the Primary switch, the NTP configuration currently present on the Primary will be replicated to the Secondary switch ' s running configuration.

Why other options are incorrect:

Options B and C: These are incorrect because they suggest configuring the sync on the Secondary switch.

Option A: While it specifies the Primary switch, vsx-sync ntp is not the correct command syntax in AOS-CX; the feature is consolidated under the broader vsx-sync time module.