If you've ever wondered how 1.1.1.1 or 8.8.8.8 can be physically located in hundreds of cities simultaneously while using a single IP address, the answer is BGP Anycast.
One Address, Many Locations
In a standard Unicast network, one IP address belongs to one specific server. In Anycast, the same IP prefix is announced by multiple routers in different geographic locations.
How Routing Decisions Are Made
When you send a request to an Anycast IP, the Border Gateway Protocol (BGP) logic on the internet's core routers determines the "shortest" path. Factors include:
- AS Path Length: How many networks the packet must cross.
- Network Proximity: Ensuring you reach the node with the least latency.
- Load Balancing: Distributing traffic across the global edge network.
Benefits of Anycast
- Lower Latency: Users automatically connect to the nearest server.
- High Availability: If one node goes down, BGP automatically redirects traffic to the next closest node.
- DDoS Mitigation: Attack traffic is localized at the edge rather than hitting a central core.