14.1 Analyzing the Current Environment

14.1 Analyzing the Current Environment

Quick Summary: The first Plan objective on HPE6-A85 is to analyze the current environment. Before anyone configures a switch or mounts an AP, someone has to document what is already there: the cabling and closets, the existing switches and their firmware, VLANs and subnets, PoE demand, the RF environment, the clients, and the services (DHCP, DNS, NTP, RADIUS, firewall rules) the new solution will depend on. Most failed deployments trace back to an assumption nobody checked at this stage.

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Why This Step Matters

An architect's design assumes certain facts: that the closet has enough power, that the cabling supports the planned speeds, that DHCP can serve the new subnets, or that the firewall allows the new APs to reach the cloud. The person doing the site work is often the first to discover that one of these assumptions is false. Catching it during analysis costs a conversation; catching it during the cutover costs an outage.

At associate level you are not expected to make design decisions, but you are expected to collect accurate facts, flag gaps, and hand them to the architect.

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What to Collect

1. Physical Plant

• Wiring closets: rack space, power circuits, UPS capacity and runtime, cooling, and grounding.
• Copper cabling: category and installed length of each horizontal run. The ANSI/TIA channel limit is 100 m. Cat5e supports 2.5GBASE-T and Cat6 supports 5GBASE-T to 100 m (IEEE 802.3bz); 10GBASE-T at 100 m needs Cat6A.
• Fiber between closets and buildings: multimode grade (OM3/OM4) or single-mode, strand counts, and lengths, because they decide which optics will work (Section 2.1).
• Labeling quality: if patch panels and cables are not labeled, the implementation will be slow and error-prone.

2. Existing Wired Network

• Inventory: switch models, serial numbers, and firmware. On AOS-CX, show system and show version give the platform and software, and show images lists the primary and secondary images.
• Topology: show lldp neighbor-info shows which device is connected to which port, the quickest way to rebuild a missing diagram.
• Port utilization: show interface brief shows which ports are up, their speed, and their mode. Count free ports and ports that will need multi-gigabit speeds.
• VLANs and Layer 2: show vlan, show spanning-tree, and show lag capture VLAN IDs, the current root bridge, and existing link aggregation.
• Layer 3: show ip interface and show ip route show where default gateways and routing live today.
• PoE: show power-over-ethernet shows the available, allocated, and drawn power per switch.

3. Wireless Environment

• Existing APs: models, mounting locations, current operating system (AOS 8 controller-based, Instant, or AOS 10), and SSIDs.
• RF conditions: coverage problems, interference sources, and DFS (radar) events in 5 GHz. A site survey confirms what the RF environment really looks like: a predictive survey models it from floor plans and wall types; a passive survey listens to existing signals; an active survey connects a test client and measures throughput.
• Client mix: how many clients per area, which support 5 GHz and 6 GHz, and which need special handling (voice handsets, scanners, medical devices, headless IoT).

4. Clients and Endpoints

• Desktop PCs and laptops that can run 802.1X.
• IP phones that need a voice VLAN and PoE.
• Headless devices (printers, cameras, sensors) that will need MAC authentication or MPSK.
• Devices with unusual power needs, such as PTZ cameras or tri-radio APs that need 802.3bt.

5. Supporting Services

• DHCP scopes and relay (ip helper-address) for every VLAN that will exist.
• DNS and NTP: cloud-managed devices validate TLS certificates, so a wrong clock or blocked NTP breaks onboarding (Section 11.2).
• Internet access from management networks: outbound HTTPS (TCP 443) to Activate and Central.
• AAA: RADIUS servers (for example ClearPass), the network device entries they will need, and existing role names.
• Firewall rules between management, user, and server networks.

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A PoE Budget Example

A closet will receive 20 APs that request Class 4, 30 IP phones at Class 2, and 6 fixed cameras at Class 3. Using the PSE-side class maximums (Section 2.2):

If the planned switch provides a 740 W PoE budget, the closet is oversubscribed in the worst case. Options include adding a second PoE switch or VSF member, using a model or power supply with a larger budget, or relying on AOS-CX allocate-by usage with PoE priorities so that critical devices keep power. That choice belongs to the designer, but the analyst must bring the numbers.

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Recording the Findings

Turn the raw data into a current-state report:

1. A topology diagram rebuilt from LLDP data.
2. An inventory table (device, model, serial, firmware, location).
3. A cabling and power summary per closet.
4. A VLAN, subnet, and service table.
5. A gap list: anything that blocks or changes the planned design, such as Cat5e runs where 5 Gbps uplinks are planned, a UPS that cannot carry the new PoE load, or a firewall that blocks outbound HTTPS.

If the environment is already managed by Central, its device inventory, topology view, and reports provide much of this information directly.

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Common Exam Traps

• Skipping services. A perfect switch configuration still fails if DHCP has no scope for the new VLAN or NTP is unreachable.
• Planning speeds from cable category alone. Length and installation quality matter; confirm with certification test results where possible.
• Using drawn power instead of class power for worst-case planning. Actual draw is useful for operations, but planning should account for what devices may request.