Latency
Latency is the amount of time it takes for a data packet to travel from the source to the destination across a network. It reflects the speed of information transfer at the infrastructure level and plays a critical role in the performance of applications, services, and network connections.
Latency is measured in milliseconds (ms) and directly affects characteristics such as webpage load times, online gaming responsiveness, video call quality, and the stability of cloud applications.
Difference from Response Time
Latency is a transport metric that shows how long it takes for a packet to traverse the network. Response time is broader: it includes latency as well as the time spent by servers or applications processing the data. For example, when accessing a website, network latency may be 30 ms, but the server’s response time could be 300 ms.
Types of Latency
- Propagation latency – the time required for a signal to travel across cables or fiber optics.
- Processing latency – time spent by routers and switches handling packets.
- Queuing latency (buffering) – extra delays caused by network congestion.
- Software latency – delays due to drivers or operating system processing.
Causes of High Latency
- large physical distance between nodes;
- overloaded networking equipment;
- weak connections (e.g., 3G instead of 4G/5G);
- use of VPNs or proxies;
- issues at the ISP or backbone level.
Applications and Importance
Monitoring latency is crucial for:
- online gaming, where smooth play is possible with ping < 50 ms;
- video conferencing, where acceptable latency is up to 150 ms;
- financial and trading systems, where even milliseconds matter;
- cloud applications and virtual desktops (VDI).
Example
A cloud service provider measures latency between its data centers and users in different regions. In Europe, the average latency is 25 ms, while in Asia it reaches 150 ms. To reduce latency, the company deploys additional CDN nodes, improving access speed and reducing customer complaints.
Frequently Asked Questions (FAQ)
Latency only shows the transport time for a packet to cross the network, while response time also includes data processing on the server or application. For example, even with low ping, a site may respond slowly due to a heavy database or overloaded server.
The most common tool is the ping command, which sends ICMP requests and records the response time in milliseconds. For more detailed diagnostics, traceroute or monitoring systems are used to identify where along the route delays occur.
For most websites, latency under 100 ms is acceptable. For online games, optimal latency is below 50 ms. In financial trading systems, even milliseconds are critical, so acceptable latency may be under 10 ms.
Packet delays cause audio and video to arrive out of sync, making voices sound delayed. This is especially noticeable on congested networks or mobile Internet, where latency may vary between 50 ms and 300 ms.
Yes. Switching from Wi-Fi to wired connections, upgrading to a faster ISP plan, and avoiding VPNs or proxies usually helps. In enterprise and global networks, CDNs and route optimization are commonly used to shorten data paths.
