Latency complaints represent some of the most frustrating support tickets ISPs handle. Customers report "slow internet" but speed tests show adequate throughput. Understanding what latency actually means—and doesn't mean—is essential for efficient troubleshooting.
Understanding Latency
Latency measures the time required for data to travel from source to destination and back. Unlike bandwidth, which describes capacity, latency describes responsiveness. A connection can have excellent bandwidth but poor latency, or vice versa. Both matter, but for different use cases.
Gaming, video calls, and real-time applications depend heavily on low latency. File downloads and streaming video care more about throughput. Customer complaints often conflate these distinct performance characteristics.
Common Latency Sources
Physical distance creates irreducible latency—light in fiber travels roughly 200,000 km/second, and routing adds hops. A packet crossing India encounters 30-60ms of base latency simply from geography.
Network congestion appears as variable latency, spiking during peak usage when queues build at bottleneck points. This manifests as inconsistent performance rather than constant slowness.
Equipment configuration issues include undersized buffers, misconfigured QoS priorities, and saturated CPUs on routing devices. These problems exist within your control and represent optimization opportunities.
Diagnostic Approaches
Traceroute reveals where latency accumulates along the path. Consistent high latency at specific hops indicates infrastructure issues; variable latency suggests congestion. Continuous monitoring tools like SmokePing graph latency over time, making patterns visible that single measurements miss.
Separate customer premises issues from network issues early. WiFi problems cause more latency complaints than network infrastructure. MTR or WinMTR combining ping and traceroute functionality helps customers participate in diagnosis.
Practical Improvements
QoS configuration ensures latency-sensitive traffic receives priority during congestion. Proper buffer sizing prevents bufferbloat. Peering arrangements reduce path length to popular destinations. Each improvement is incremental, but cumulative effects significantly enhance perceived performance.
Managing customer expectations matters as much as technical optimization. Some latency is physics—no network engineering eliminates it.