When you type www.someplace.com into the address bar of your browser and press enter, the site is displayed in your browser in (hopefully) a few seconds. There are a number of things happening behind the scenes to route your request to that
When you type www.someplace.com into the address bar of your browser and press enter, the site is displayed in your browser in (hopefully) a few seconds. There are a number of things happening behind the scenes to route your request to that site so you can view the content. Border gateway protocol (BGP) ensures that your request arrives at the server for that site via the best route through the internet.
There are a few methodologies to address the target server, and in this post we will discuss one of them, anycast addressing, in detail.
What is Anycast?
In anycast, a collection of servers share the same IP address and send data from a source computer to the server that is topographically the closest. This helps cut down on latency and bandwidth costs, improves load time for users, and improves availability. It is important to remember that topographically closer does not inherently mean geographically closer, though this is often the case.
Anycast is linked with the BGP protocol which ensures that all of a router’s neighbors are aware of the networks that can be reached through that router and the topographical distance to those networks. The main principle of anycast is that an IP address range is advertised in the BGP messages of multiple routers. As this propagates across the Internet, routers become aware of which of their neighbors provides the shortest topographical path to the advertised IP address.
These other primary addressing methods are available to route traffic.
- Unicast addressing uses a one-to-one association, where each destination address is uniquely identified as a single receiver endpoint. Traditional DNS deployments are configured with unicast addresses.
- Multicast addressing uses a one-to-unique many association, where datagrams are routed from a single sender to multiple selected endpoints in a single transmission, using a multicast group address. A common use of multicast is streaming audio, where the audio is published via multicast addressing and clients pick up the routed stream as a channel.
- Broadcast addressing uses a one-to-many association, where datagrams are routed from a single sender to all other connected endpoints in a single transmission, using a broadcast address. The network automatically replicates datagrams as needed for all network segments (links) that contain an eligible receiver.
With Unicast, DNS client resolvers can be configured with multiple DNS n