Argo Smart Routing extends to UDP
Cloudflare has announced that Argo Smart Routing, its traffic acceleration product, now supports UDP traffic. The feature, previously limited to HTTP and TCP-based protocols, is designed to cut latency, packet loss, and jitter for UDP applications such as online games, voice calls, and video conferencing. In testing, round-trip time (RTT) dropped by as much as 17% on a trans-Pacific route.
Why UDP matters for real-time applications
Most web traffic travels over TCP, a protocol built around reliability. If a packet is lost, TCP retransmits it, which is essential when loading a full webpage where every element matters. Even newer protocols like HTTP/3, though built on QUIC instead of TCP, preserve that retransmission behavior.
But not every application needs perfect delivery. Real-time communications (RTC) and gaming are more concerned with freshness than completeness. In a live video call or an online match, retransmitting a lost packet is often pointless—by the time it arrives, the moment has passed. These applications therefore rely on UDP, which sends packets quickly without guaranteeing they arrive.
Latency is the critical metric here. In gaming, higher RTT means slower reactions and visible jitter as other players' positions update. In video meetings, delay causes participants to talk over each other. Even when providers deploy servers close to users, a call between, say, Amsterdam and Los Angeles still crosses thousands of miles, and the longer the path, the greater the chance of congestion causing delays and dropped packets.
How Argo Smart Routing selects a path
Argo Smart Routing acts as a traffic router, using real-time measurements to pick the best path across the Internet. It continuously sends millions of synthetic probes from every Cloudflare data center to each customer's origin, measuring the latency of all possible routes. This data is combined with inter-datacenter probe results to calculate the optimal route when a user makes a request. The same route computation logic used for HTTP and TCP traffic has now been extended to UDP.
The approach has already shown benefits for HTTP traffic, reducing time to first byte by up to 30% on average. Because networks often treat UDP differently than TCP, Cloudflare ran a dedicated test to verify the gains would carry over.
Measured improvements across the Pacific
In the validation test, an origin was hosted in Iowa and a client connected from Tokyo. Using standard Spectrum proxying, the average RTT was 173.3 ms. With Argo Smart Routing enabled, that dropped to 143.3 ms—an average reduction of 17.3% and an effective shortening of the route by over 1,000 miles across a 6,074-mile (9,776 km) span.
Argo Smart Routing for UDP is currently in closed beta. Cloudflare is inviting gaming, RTC, and other UDP-heavy services with a use case for lower-latency traffic to apply via their account team.
