Jitter
Variation in packet arrival times. Low jitter means consistent latency. High jitter means packets arrive at unpredictable intervals. Critical for video streaming and real-time applications.
Full Explanation
If your average latency is 20ms but individual packets arrive at 5ms, 50ms, 10ms, 40ms, that's high jitter. The average looks fine but the inconsistency causes problems. Video players stutter, WebSocket connections feel laggy, and real-time protocols break down.
For CDN-delivered video, jitter is managed by the player's buffer. The player downloads segments ahead of time to smooth out network irregularities. But if jitter is severe enough to empty the buffer, the user sees rebuffering. Low-latency live streaming is especially sensitive because the buffer is intentionally small.
CDNs reduce jitter by serving from nearby PoPs (shorter paths have less variation), using private backbones (controlled network conditions), and employing congestion control algorithms that prioritize consistent delivery over raw speed.
Examples
# Measure jitter with ping
$ ping -c 20 cdn.example.com
round-trip min/avg/max/mdev = 4.2/5.1/8.3/1.2 ms
# ^^^ mdev = jitter
# Low jitter: mdev < 2ms
# High jitter: mdev > 10ms
# iperf3: measure jitter on UDP
$ iperf3 -c cdn.example.com -u -b 10M
[ 5] 0.00-10.00 sec Jitter: 0.234 ms
# Check jitter impact on video:
# Buffer = 4 seconds, Segment = 2 seconds
# Jitter > 2 seconds = risk of rebufferingVideo Explanation
Frequently Asked Questions
Variation in packet arrival times. Low jitter means consistent latency. High jitter means packets arrive at unpredictable intervals. Critical for video streaming and real-time applications.
# Measure jitter with ping
$ ping -c 20 cdn.example.com
round-trip min/avg/max/mdev = 4.2/5.1/8.3/1.2 ms
# ^^^ mdev = jitter
# Low jitter: mdev < 2ms
# High jitter: mdev > 10ms
# iperf3: measure jitter on UDP
$ iperf3 -c cdn.example.com -u -b 10M
[ 5] 0.00-10.00 sec Jitter: 0.234 ms
# Check jitter impact on video:
# Buffer = 4 seconds, Segment = 2 seconds
# Jitter > 2 seconds = risk of rebufferingRelated CDN concepts include:
- Last Mile — The final network segment between the ISP's infrastructure and the end user's device. Often the …
- Latency — The time delay between a request and the start of its response. For CDNs, it's …
- RTT (Round-Trip Time) (RTT) — The time it takes for a packet to travel from client to server and back. …
- Throughput — The actual amount of data transferred per unit of time. Unlike bandwidth (maximum capacity), throughput …