How Anycast Transforms DDoS Defense: From Detection to Global Traffic Dilution

DDoS Protection Overview

Before dedicated traffic‑scrubbing products, operators relied on routing blackhole, router ACLs, and firewall access control, which could not detect application‑layer attacks or handle massive traffic volumes.

Hardware‑based scrubbing appliances later appeared, but as attack sizes grew (e.g., GitHub’s 1.35 TB peak) and enterprises expanded overseas, on‑premise devices became insufficient and costly.

Cloud‑based anti‑DDoS services emerged, leveraging the global compute capacity of cloud providers to offer scalable traffic cleaning while reducing hardware procurement and deployment expenses.

UCloud DDoS High‑Protection Architecture

The system is organized into three core modules: detection, linkage, and cleaning.

1. Detection System

Traffic entering the WAN Border Router (WBR) is mirrored to a detection cluster. Algorithms analyze the flow, identify attacked EIPs, store evidence, and notify the linkage system.

2. Linkage System

Upon receiving alerts, the linkage component decides whether to block the traffic (by invoking the carrier’s blackhole API) or forward the flow to the cleaning system.

3. Cleaning System

The cleaning cluster strips malicious packets, restores legitimate traffic, and reinjects it into the main path, protecting internal network devices from overload.

Why Traffic Dilution Is Needed

When attack volume exceeds the capacity of a single scrubbing node or the upstream carrier link, cleaning becomes ineffective. Diluting traffic across multiple points reduces the load on any single device.

Anycast Technology

Anycast assigns a single IP address to multiple geographically distributed servers. BGP routes client packets to the nearest server, combining the uniqueness of unicast with the one‑to‑many distribution of multicast.

Typical use cases include Google Public DNS (8.8.8.8), which benefits from fast, reliable resolution worldwide.

How Anycast Dilutes DDoS Traffic

During an attack, BGP directs malicious packets to multiple announced Anycast nodes, spreading the load across regions. UCloud’s overseas nodes announce the same Anycast address, enabling global traffic dispersion and localized scrubbing.

UCloud Anycast Solution Features

Multi‑region proximity access: The same IP is announced in many overseas locations, routing traffic to the nearest UCloud backbone and dedicated lines.

Multi‑origin processing: Identical IPs bind to servers in multiple regions, allowing requests to be handled locally.

Distributed global cleaning: Attack traffic is redirected to regional entry points where it is cleaned before reaching the core network.

Conclusion

DDoS attack vectors and peak volumes continue to rise, making it impossible to guarantee complete protection. Effective mitigation requires coordinated effort among governments, carriers, standards bodies, security vendors, and end users, with solutions such as Anycast‑based traffic dilution playing a key role.