ICMP Monitor (Ping)

Monitor basic network connectivity using ICMP echo requests (ping). Verify server reachability and measure round-trip time (RTT).

What is an ICMP Monitor?

An ICMP Monitor sends ICMP Echo Request packets (ping) to a target host and waits for Echo Reply packets. It measures latency and detects packet loss.

Use Cases

Basic Reachability: Verify servers are online
Network Latency: Measure round-trip time
ISP Monitoring: Track internet connection stability
Firewall Testing: Verify ICMP is not blocked
Routing Issues: Detect network path problems

Configuration Options

Basic Configuration

Field	Description	Example
Name	Human-readable identifier	Production Server Ping
Host	Hostname or IP address	server.example.com or 8.8.8.8
Packet Count	Number of ping packets to send	3 (default), 5, 10
Packet Loss Threshold	Max acceptable packet loss %	10%, 20%, 50%
Latency Threshold	Max acceptable RTT (ms)	100ms, 500ms, 1000ms
Interval	Check frequency	15s, 30s, 60s, 5m
Timeout	Max wait time per packet	5s, 10s, 30s

Configuration Examples

Basic Server Reachability

{
  "type": "icmp",
  "name": "Production Server",
  "host": "server.example.com",
  "packetCount": 3,
  "packetLossThreshold": 20,
  "interval": 60000,
  "timeout": 10000
}

Latency-Sensitive Monitoring

{
  "type": "icmp",
  "name": "CDN Edge Server",
  "host": "cdn.example.com",
  "packetCount": 5,
  "latencyThresholdMs": 50,
  "packetLossThreshold": 10,
  "interval": 30000
}

ISP Uptime Monitoring

{
  "type": "icmp",
  "name": "ISP Gateway",
  "host": "8.8.8.8",
  "packetCount": 10,
  "packetLossThreshold": 30,
  "interval": 60000
}

Multi-Region Latency Check

{
  "type": "icmp",
  "name": "Global Latency Check",
  "host": "api.example.com",
  "packetCount": 5,
  "latencyThresholdMs": 200,
  "locations": ["us-east", "eu-west", "asia-pacific"]
}

Check Results

Metrics Collected

Each ICMP check provides:

Packets Sent: Total packets transmitted
Packets Received: Packets that returned
Packet Loss %: (Sent - Received) / Sent × 100
Min RTT: Fastest round-trip time
Avg RTT: Average round-trip time
Max RTT: Slowest round-trip time
Std Dev: Latency variation

Example Output

{
  "status": "up",
  "packetsSent": 5,
  "packetsReceived": 5,
  "packetLoss": 0,
  "rttMin": 12.5,
  "rttAvg": 15.3,
  "rttMax": 18.7,
  "rttStddev": 2.1
}

Failure Conditions

1. Total Packet Loss

All packets lost (0% received). Indicates:

Host is down
Network is unreachable
ICMP is blocked by firewall

2. High Packet Loss

Packet loss exceeds threshold. Indicates:

Network congestion
Intermittent connectivity
Firewall dropping packets

3. High Latency

RTT exceeds threshold. Indicates:

Network congestion
Long routing path
Bandwidth saturation

Best Practices

1. Use as First Line of Defense

ICMP is the most basic check. Use it to detect:

Server completely offline
Network connectivity lost

Then layer on TCP and HTTP monitors for application health.

2. Send Multiple Packets

Sending 3-5 packets provides more accurate measurements:

Averages out transient spikes
Detects intermittent packet loss
More reliable than single packet

3. Set Realistic Thresholds

Scenario	Packet Loss	Latency
Local network	0-5%	<10ms
Same region	0-10%	<50ms
Cross-region	0-20%	<200ms
International	0-30%	<500ms

4. Monitor from Multiple Locations

Check from 2-3 regions to identify:

Regional network outages
ISP-specific issues
Routing problems

5. Combine with Other Monitor Types

ICMP only tests network layer. Also use:

TCP: Verify ports are open
HTTP: Verify application responds

Troubleshooting

100% Packet Loss

Possible Causes:

Host is down
Firewall blocks ICMP
Network is unreachable
DNS resolution failed

Solution:

Test manually:
```
ping -c 5 server.example.com
```

Check if host is up:

# Try TCP instead (port 80/443)
nc -zv server.example.com 80

Verify DNS:
```
nslookup server.example.com
```

Check firewall allows ICMP:

# Allow ICMP echo requests
sudo iptables -A INPUT -p icmp --icmp-type echo-request -j ACCEPT

High Latency

Possible Causes:

Network congestion
Geographic distance
Poor routing
ISP throttling

Solution:

Check routing path:
```
traceroute server.example.com
```
Adjust threshold to match expected latency
Use CDN or edge locations closer to users

Intermittent Packet Loss

Possible Causes:

Network congestion
Wi-Fi interference (if wireless)
Rate limiting

Solution:

Increase packet count for better averaging
Raise packet loss threshold (e.g., 20-30%)
Check network during peak hours

Limitations

1. ICMP Can Be Blocked

Many firewalls and cloud providers block ICMP for security. If ICMP is blocked:

Use TCP monitors instead
Whitelist monitoring IPs
Enable ICMP in firewall rules

2. Doesn't Test Application Health

ICMP only verifies network connectivity. It doesn't check:

Services are running
Application responds
Ports are open

3. Low Priority in Networks

ICMP is often deprioritized by routers. High ICMP latency may not reflect actual application latency.

Common Targets

Public DNS Servers (ISP Monitoring)

Google: 8.8.8.8, 8.8.4.4
Cloudflare: 1.1.1.1, 1.0.0.1
Quad9: 9.9.9.9

Your Infrastructure

Web servers: api.example.com
Database servers: db.example.com
Load balancers: lb.example.com
Gateways: gateway.example.com

Next Steps

TCP Monitor: Monitor specific ports
HTTP Monitor: Monitor web endpoints
Configure Alert Rules for your ICMP monitors
Best Practices for effective monitoring