IP SLA — Proactive Health Checks

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Learning Objectives

Explain why IP SLA beats waiting for a user complaint
Configure a basic ICMP echo SLA probe
Build a latency tracker that flags SLA violations

Catch It Before Users Do

IP SLA schedules synthetic tests -- automated pings/traces the router runs on its own -- so you find out latency to the data center spiked at 30 seconds, not when a user calls the help desk an hour later.

Real Cisco IOS syntax -- reference only.

ip sla 1
 icmp-echo 192.168.1.1
 frequency 30
ip sla schedule 1 life forever start-time now

show ip sla statistics

Practice — Latency Tracker

A simulated batch of probe results and a basic threshold check.

probe_results_ms = [12, 14, 13, 95, 11, 13]
THRESHOLD_MS = 50

violations = [r for r in probe_results_ms if r > THRESHOLD_MS]
print(f"Violations: {violations}")

📝 Exercise: Build an SLA Monitor

Write a function check_sla(probe_results_ms, threshold_ms) that returns a dict with keys 'average', 'max', and 'violations' (count of readings above threshold). Then run it against the sample data and print a one-line health summary.

code.py

probe_results_ms = [12, 14, 13, 95, 11, 13, 120, 14]

def check_sla(probe_results_ms, threshold_ms):
    average = sum(probe_results_ms) / len(probe_results_ms)
    return {
        "average": round(average, 1),
        "max": max(probe_results_ms),
        "violations": sum(1 for r in probe_results_ms if r > threshold_ms),
    }

result = check_sla(probe_results_ms, threshold_ms=50)
status = "DEGRADED" if result["violations"] > 0 else "HEALTHY"
print(f"avg={result['average']}ms max={result['max']}ms violations={result['violations']} -> {status}")

Output

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