[Day 40] Cisco ISE Mastery Training: End-to-End Wired Authentication Lab Validation

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Introduction

In Cisco ISE deployments, lab validation is not just a “nice to have” — it’s the only way to confirm that your authentication policies work exactly as intended before you deploy them in production.
End-to-end wired authentication lab validation means verifying every step of the authentication workflow:

• Supplicant configuration (Windows/macOS/Linux)
• Switch 802.1X control plane
• RADIUS request/response flow
• ISE policy matches and authorization results

Skipping this validation step is like building a bridge without a load test — it might look fine, but the moment traffic flows, cracks appear. Today, we’re going beyond theory — performing hands-on validation using both ISE GUI and switch CLI.

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Problem Statement

Many engineers configure wired authentication in Cisco ISE, see “Success” on one test device, and assume all is well.
In reality:

• A policy mismatch might still allow some devices through in “Monitor Mode” without enforcing security.
• Certificates might be valid on one OS type but fail on another.
• Switchports might silently default to MAB when EAP packets drop.
• Timeouts and VLAN assignments might work in one VLAN but fail in another.

Without full end-to-end lab validation, these issues reach production and cause either:

1. Security holes (bypass of NAC enforcement), or
2. Access outages (critical devices losing network).

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Solution Overview

Cisco ISE’s Live Logs, Live Sessions, RADIUS Diagnostics, and Endpoint Identity Groups combined with switch CLI session checks provide a full chain of visibility.
We validate:

• Supplicant sends EAPOL-Start
• Switch relays authentication to ISE
• ISE matches correct policy set
• RADIUS Access-Accept returns correct authorization profile
• Switch applies ACL/VLAN/DACL dynamically
• Session stays active and re-authenticates when needed

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Sample Lab Topology

Text Description:

• Platform: VMware ESXi or EVE-NG
• ISE: Cisco ISE 3.x VM (2 vCPU, 16GB RAM)
• Switch: Catalyst 9300 (EVE-NG or physical)
• Endpoints:
  • Windows 10 wired supplicant
  • macOS wired supplicant
  • Linux wired supplicant
• Connectivity: Switch uplink to ISE, endpoints in access VLAN with 802.1X enabled.

Diagram Description:

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Step-by-Step GUI & CLI Validation Guide

Step 1 – Check Switchport Authentication Status

show authentication sessions interface Gi1/0/10 details

Look for:

• Status: Authc Success
• Method: dot1x
• VLAN: 20 (matches ISE authorization profile)

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Step 2 – Verify ISE Live Logs

1. Navigate to:
   Operations → RADIUS → Live Logs
   [Screenshot: ISE Live Logs Success Entry]
2. Confirm:
   • Authentication method (EAP-TLS, PEAP)
   • Policy Set name matched
   • Authorization Profile applied

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Step 3 – Check ISE Live Sessions

1. Go to:
   Operations → RADIUS → Live Sessions
   [Screenshot: ISE Live Sessions Active State]
2. Verify:
   • Active session for each endpoint
   • Endpoint MAC, IP, and assigned VLAN/DACL

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Step 4 – Verify Certificate Authentication

For EAP-TLS:

• Go to Administration → Certificates → Certificate Management → System Certificates
• Ensure CA cert is trusted and endpoint cert is valid.
• From endpoint:

openssl s_client -connect ise.domain.com:443 -showcerts

Confirm the CA chain.

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Step 5 – Force Re-Authentication

On switch:

clear authentication session interface Gi1/0/10

Re-check Live Logs for EAPOL start and Access-Accept.

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Step 6 – Test Authorization Profile Enforcement

• Change the user group in AD or ISE Endpoint Identity Group.
• Disconnect/reconnect endpoint.
• Confirm new VLAN/DACL applied via:

show authentication sessions interface Gi1/0/10 details

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Step 7 – Negative Testing

• Intentionally fail authentication (wrong password/cert).
• Confirm ISE returns Access-Reject and switch moves to Restricted VLAN.
• [Screenshot: ISE Live Logs Failure Reason]

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Step 8 – Multi-OS Validation

• Test on Windows, macOS, and Linux to ensure policy hits are consistent.
• Review logs for each OS in ISE.

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Step 9 – Log Export

From ISE:
Operations → Reports → RADIUS Authentication → Export for audit.

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Step 10 – Final Health Check

On switch:

show access-session
show run | section interface Gi1/0/10

On ISE:
Administration → System → Logging → Log Configuration to ensure future troubleshooting is possible.

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FAQs

1. Why does my switch show “Authc Success” but ISE Live Logs don’t have an entry?

Answer: This happens when the session was already authenticated earlier and is cached in the switch’s session table. The switch does not re-trigger RADIUS unless you clear the session:

clear authentication session interface Gi1/0/x

Then check Live Logs again.

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2. My ISE policy hits for Windows but fails for macOS/Linux. What’s different?

Answer: Different OSes have different 802.1X supplicant defaults.

• Windows uses PEAP-MSCHAPv2 unless changed.
• macOS often defaults to EAP-TLS if a certificate exists.
• Linux depends on wpa_supplicant config.
  Match your policy conditions accordingly.

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3. How do I confirm if a DACL from ISE is actually enforced on the switch?

Answer:

1. Run:

show authentication sessions interface Gi1/0/x details

Look for IPv4 ACL Name: <dacl_name>
2. Verify ACL existence:

show ip access-lists <dacl_name>

If not present, the switch didn’t download it — check RADIUS and CoA logs.

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4. Why does MAB fallback trigger even when my device supports 802.1X?

Answer: Likely due to EAP timeout or supplicant not sending an EAPOL-Start. Increase timers on the switch:

dot1x timeout quiet-period 5
dot1x timeout tx-period 10

Ensure supplicant is enabled before the port comes up.

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5. How do I see the exact ISE policy rule matched for a session?

Answer: In ISE Live Logs, click the timestamp → Details → Steps tab.
It shows each policy condition check and where it matched/fell through.

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6. My VLAN assignment from ISE works for some users but not others. Why?

Answer: Common reasons:

• Switchport is not in switchport mode access.
• VLAN is not present or allowed on uplinks.
• Voice VLAN conflict (if IP phone connected).
  Verify switch config and trunking.

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7. How can I test certificate expiry enforcement in ISE?

Answer:

• Issue a short-lived cert (1–2 days) from your CA.
• Assign it to the endpoint.
• Wait for expiry and force re-authentication.
  ISE will fail EAP-TLS if cert is expired.

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8. Why is my ISE showing “RADIUS Request Dropped” during testing?

Answer: Usually due to:

• Incorrect RADIUS shared secret
• Mismatched source interface on switch
• Missing network device entry in ISE
  Run:

show run | include radius-server

and verify ISE Network Devices config.

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9. Can I validate authentication without kicking live users off?

Answer: Yes. Use an unused switchport for testing. Or set the port in Monitor Mode (authentication open) to log auth attempts without enforcement.

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10. What’s the fastest way to export my validation results for audit or training?

Answer:

• Go to ISE Reports → RADIUS Authentication
• Filter by device MAC or username
• Click Export CSV
• Include switch CLI outputs for proof of enforcement

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YouTube Link

For more in-depth Cisco ISE Mastery Training, subscribe to my YouTube channel Network Journey and join my instructor-led classes for hands-on, real-world ISE experience

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7. Deep-Dive Closing Notes

End-to-end lab validation ensures your Cisco ISE wired authentication isn’t just “configured” — it’s proven.
You’re not relying on assumptions; you’re working from hard data, cross-validated between switch CLI and ISE GUI.
This process catches 90% of policy, supplicant, and switch config issues before production.

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