DSL Network Guide Chapter 9: Access Concentrators (Redbacks)

Click to view full picture.

Access concentrators have various names. The most commonly used name is redback, after the leading manufacturer of said devices. For the purpose of this tutorial we will refer to them as redbacks.
The redback is in charge of your connection, also known as aggregating your connection. It is the middle-man of your connection. Everything you want to do is done by requesting the redback for it. The redback takes responsibility of contacting the proper servers and relaying the service back to you.
Your whole entire internet session is handled by your redback. When you first connect the redback goes to the appropriate server and verifies that you indeed have access to be part of the network. Once that is verified the redback issues you an IP address and start your session. It takes care of all your requests for the period of your session. When your request to disconnect the redback takes care of notifying all the proper servers it can release your information and lets you go.
Each redback can only handle so many customers. Most ISPs have a load balancing program that determines if one redback is becoming overloaded and will switch customers off it and move them to a redback that has more availability. If you have someone run a traceroute to your IP the second-to-last hop is your redback. If you pay attention you should notice that you will usually stay on the same redback for quite some time.

<-Back Table of Contents Next->