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Network latency -- the time that elapses between a request for data and the delivery of that communication -- can have a serious effect on the end-user experience. Sometimes confused with throughput -- the amount of data that can be moved through the network during a given time period -- network latency is the round-trip time from data query to receipt. Usually measured in milliseconds, if that delay is too long, then it can disrupt communications.
High network latency dramatically increases webpage load times, interrupts video and audio streams, and renders an application unusable. Depending on the application, even a relatively small increase in latency can have enough of a negative effect on communications to prompt impatient end users to abandon a webpage.
A number of factors can introduce latency, starting with the transmission mechanism itself. For example, a low quality or poorly maintained fiber optic cable can delay transmissions. Routing and switching errors can also slow down transmissions. Other elements can delay communications, including storage system inefficiencies, end-user software processing issues, and security services that parse and reassemble packets.
Fortunately, network managers can take some straightforward steps to reduce and improve network latency and optimize the end user's experience.
Measure packet delay
To improve network latency, start by having an accurate measure of how long a network communication takes from point of origin to fulfillment. Network managers have a number of tools to choose from to do this, including Ping, Traceroute and My traceroute (MTR).
Ping records a packet's round-trip time from the initial source to the final destination. Traceroute visualizes the path that packets take across an IP network, recording latency between each host on the route. MTR blends elements of both Ping and Traceroute to track both the delay between devices on the path and the total transit time.
These measurement tools identify potential bottlenecks, particularly if it is an equipment problem or network configuration issue. If the underlying cause is a topology issue, IT can use network optimization tools to address network congestion by improving routing to dodge bottlenecks.
If the concern is the transmission medium itself, network managers can employ regenerators or amplifiers to increase speeds on the network. However, amplification techniques could also introduce latency.
Caching and compression
One of the major reasons for poor latency is geography. Highly distributed IP networks traverse vast distances, adding transmission time that can derail an application. One way to address this is to take a page from content delivery networks (CDNs) by having an edge server located near end users. This will shorten the expanse that packets have to travel and reduce page load times from web servers.
CDN providers often use techniques such as file compression and image optimization to reduce the amount of bandwidth needed to transfer high volumes of data. These techniques can also limit and improve network latency.