Ping
How Telescope checks host reachability and latency with ICMP, including TCP fallback behavior.
Ping monitors test network-level reachability for a target host. They send ICMP echo requests, measure latency, and classify packet-loss conditions.
How a check works
- Telescope resolves the host from
target(or URL hostname fallback). - The worker runs an OS-level
pingcommand with bounded packet count and timeout. - It parses packet statistics (sent/received/loss) and RTT values (min/avg/max/stddev when available).
- If ICMP is unavailable or fully blocked and fallback is enabled, Telescope can run a TCP connect probe as fallback.
- The result is recorded with protocol metadata (
icmportcp).
Status classification
| Condition | Status | What it means |
|---|---|---|
| Reachable, low packet loss, acceptable latency | Up | Host is reachable and healthy |
| Partial packet loss over threshold | Degraded | Host is reachable but unstable |
| Average latency above threshold | Degraded | Host is reachable but slow |
| Zero replies / high loss over down threshold | Down | Host appears unreachable or severely degraded |
If ICMP fails and TCP fallback succeeds, the check result includes protocol: "tcp" with fallback metadata.
Configuration options
These values are stored in monitor config and accept both camelCase and snake_case keys:
| Setting | Default | Description |
|---|---|---|
packetCount | 4 | Number of ICMP packets per check |
packetTimeoutMs / timeout | 5000 | Per-packet timeout target |
intervalMs / interval | 1000 | Delay between packets |
lossDegradedThreshold | 10 | Packet-loss % to mark degraded |
lossDownThreshold | 50 | Packet-loss % to mark down |
highLatencyThresholdMs | unset | Optional avg RTT threshold for degraded |
fallbackToTcp | true | Enable TCP connect fallback if ICMP is unavailable |
tcpPort | 443 | Preferred TCP fallback port |
Result data highlights
Ping checks store structured metrics in result_data, including:
protocol(icmportcp)packets_sent,packets_received,packet_loss_percentlatency_min_ms,latency_avg_ms,latency_max_ms,latency_stddev_msfallback_used,fallback_port,icmp_error
Operational note
Some environments block ICMP or do not expose the ping binary. TCP fallback reduces false negatives in those cases, but ICMP-specific latency/loss metrics are only available when protocol is icmp.