• Trainer Sagar Dhawan
• Posted on September 5, 2025
• No Comments

[Day 101] Cisco ISE Mastery Training: Large-Scale Distributed Deployment Design

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Introduction

Designing Cisco ISE for large-scale enterprise deployments is not a simple “add another node” exercise. It’s about engineering a security access fabric that:

• Serves hundreds of thousands of endpoints concurrently.
• Stays resilient across multiple data centers.
• Ensures authentication latency stays low even under load.
• Provides real-time visibility & troubleshooting without performance trade-offs.

A Large-Scale Distributed Deployment (LSDD) typically includes:

• Dedicated Policy Service Nodes (PSNs): Scalable authentication engines.
• Policy Administration Nodes (PANs): Centralized control + redundancy.
• Monitoring Nodes (MnTs): Centralized logging/visibility with redundancy.
• Load Balancers: To distribute RADIUS/TACACS load across PSNs.
• Replication & Synchronization: PAN → PSNs, MnT cluster consistency.

This workbook is designed as a practical masterclass:
Every section includes step-by-step GUI configuration and CLI validation so you don’t just configure — you also verify and troubleshoot like TAC engineers.

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Problem Statement

The Challenge:
Small ISE clusters scale poorly in enterprise environments. Problems include:

• Authentication bottlenecks when thousands of users log in simultaneously.
• Single points of failure when PAN/MnT is not redundant.
• Slow policy propagation across nodes.
• Logging gaps when MnT fails.
• Inefficient RADIUS load balancing without proper PSN design.

Without a distributed design, enterprises risk:

• User downtime due to overload.
• Compliance failures (missing logs).
• Weak security enforcement at global scale.

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Solution Overview

Cisco ISE Large-Scale Deployment Architecture provides:

1. PAN redundancy → Primary & Secondary.
2. PSN scalability → Multiple PSNs behind load balancers (F5, ACE, Citrix).
3. MnT clustering → Active/Standby or Split for log redundancy.
4. Replication model → PAN is the single point of config changes → syncs to PSNs/MnTs.
5. Geo-redundancy → Deploy nodes across multiple DCs.
6. CLI & GUI health checks → Validate node sync, replication, session load.

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Sample Lab Topology

Lab Environment:

• Platform: VMware ESXi / EVE-NG.
• Nodes:
  • 2x PAN (Primary + Secondary).
  • 4x PSN (behind load balancer).
  • 2x MnT (Active/Standby).
• Network Devices:
  • Cisco Switch with 802.1X + MAB enabled.
  • Cisco WLC for wireless integration.
• Endpoints:
  • Windows 10 laptops.
  • BYOD + corporate devices.

Topology Diagram:

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Step-by-Step GUI & CLI Configuration Guide

Step 1: Enable Large Deployment Mode

• GUI:
  1. Navigate to Administration > System > Deployment.
  2. Select Enable PAN & MnT redundancy.
  3. Apply changes.

• CLI Validation:

ise/admin# show application status ise
ise/admin# show running-config ise

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Step 2: Add Secondary PAN

• GUI:
  1. Go to Administration > System > Deployment.Register new node. Assign Admin role → mark as Secondary PAN.

• CLI Validation:

ise/admin# show logging system
ise/admin# show application status ise | include Admin

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Step 3: Add Multiple PSNs

• GUI:
  1. Register node. Assign PSN role.
  2. Repeat for all nodes.
  3. Add them behind load balancer.
• CLI Validation (on PSN):

ise/psn# show application status ise
ise/psn# show radius statistics
ise/psn# show sessions

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Step 4: Configure MnT Clustering

• GUI:
  1. Register MnT node → select Monitoring role.
  2. Configure one as Active, other as Standby.
• CLI Validation:

ise/mnt# show logging system
ise/mnt# show running-config ise

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Step 5: Verify Replication & Node Health

• GUI:
  • Administration > System > Deployment → Node Status
• CLI:

ise/admin# show replication status
ise/admin# show application status ise

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FAQs – Large-Scale Cisco ISE Distributed Deployment

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1. How many nodes can a single Cisco ISE deployment support?

Answer:

• Cisco ISE supports up to 50 nodes in a single deployment (ISE 3.x).
• You can have 2 PANs (Primary + Secondary), 2 MnTs, and multiple PSNs depending on scale.
• Node roles are distributed:
  • PAN: Centralized configuration.
  • PSN: Authentication/Authorization runtime.
  • MnT: Centralized logging.

Validation:

• GUI: Administration > System > Deployment → Check node list.
• CLI:

ise/admin# show application status ise
ise/admin# show running-config ise

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2. What is the recommended node role distribution in a large deployment?

Answer:

• PAN (2 nodes) → 1 Primary + 1 Secondary (DR site).
• MnT (2 nodes) → 1 Active + 1 Standby.
• PSN (Scalable) → Usually 4–20 nodes behind load balancers.
• Keep PAN/MnT roles separate from PSN in production to reduce overhead.

Tip: PAN+MnT can coexist, but in large-scale >25k endpoints, separate them.

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3. How does load balancing for PSNs work in practice?

Answer:

• Use external load balancer (F5, Citrix, ACE) to distribute RADIUS/TACACS+ requests across PSNs.
• Load balancer must support persistence (“stickiness”) so the same session stays on one PSN.
• Recommended method: Source-IP based persistence.

Validation:

• GUI: Operations > RADIUS > Live Sessions → Session distribution.
• CLI:

ise/psn# show radius statistics
ise/psn# show sessions

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4. What happens if the Primary PAN fails?

Answer:

• The Secondary PAN remains in standby mode until you promote it manually.
• Configuration changes can only be made on active Primary PAN.

Failover Test:

• GUI: Administration > System > Deployment → Promote Secondary PAN.
• CLI:

ise/admin# application configure ise

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5. Can PSNs be geographically distributed across multiple data centers?

Answer:

• Yes, PSNs are often deployed at branch/DC sites for local authentication.
• Latency requirement: RADIUS/EAP must be <300 ms round trip.
• All PSNs sync policies from the PAN automatically.

Tip: Always use local PSNs in large campuses to reduce WAN latency.

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6. How does ISE replication work between nodes?

Answer:

• PAN → PSNs & MnTs push replication.
• Config changes are done only on Primary PAN → auto-sync to other nodes.
• MnT log replication works in active/standby mode.

Validation:

• GUI: Administration > System > Deployment → Replication Status.
• CLI:

ise/admin# show replication status

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7. What are the hardware/sizing guidelines for LSDD?

Answer:

• PAN: 16 vCPUs, 32 GB RAM, 600 GB disk (for >25k endpoints).
• PSN: 8–16 vCPUs, 32 GB RAM.
• MnT: 16 vCPUs, 64 GB RAM, 2 TB disk (for long-term log storage).

Reference: Cisco ISE Performance & Scale guide.

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8. What’s the best way to monitor PSN load and session health?

Answer:

• GUI: Operations > Live Sessions → Per-PSN session view.
• CLI:

ise/psn# show sessions
ise/psn# show radius statistics
ise/psn# show application status ise

• Use SNMP/REST APIs for external monitoring tools (SolarWinds, Splunk, etc).

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9. Can MnT nodes be deployed across data centers?

Answer:

• Yes, but ensure latency <300 ms.
• Logs replicate between active/standby.
• In large-scale, often one MnT per DC for local log redundancy.

Tip: Always integrate MnT with external syslog/SIEM for compliance.

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10. What are the top failure scenarios to validate in LSDD labs?

Answer:

1. Primary PAN failure → Secondary PAN promotion.
2. PSN outage → Load balancer reroutes sessions.
3. MnT failover → Verify logs continue in standby.
4. WAN link failure → Local PSN handles authentication.
5. Replication break → Policies not updating on remote PSNs.

CLI Tools:

ise/admin# show logging system
ise/admin# show application status ise
ise/psn# show radius statistics

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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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Closing Notes

Large-Scale Deployment of Cisco ISE is about scalability, high availability, and distributed control.

• Separate roles (PAN, PSN, MnT) for efficiency.
• Use load balancing for PSNs.
• Always validate replication and session load via GUI + CLI.

By mastering LSDD, you’re operating at the CCIE-level of ISE expertise, capable of building carrier-grade NAC infrastructures.

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Upgrade Your Skills – Start Today

For more in-depth Cisco ISE Mastery Training, subscribe to my YouTube channel Network Journey and join my instructor-led 4-month CCIE Security training.

Course outline: https://course.networkjourney.com/ccie-security/

Take the Fast-Track to Cisco ISE Mastery Pro and become the engineer that enterprises trust to run their global NAC deployments.

Enroll Now & Future‑Proof Your Career
Email: info@networkjourney.com
WhatsApp / Call: +91 97395 21088

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