Peering - How Peering Works

How Peering Works

The Internet is a collection of separate and distinct networks, each one operating under a common framework of globally unique IP addressing and global BGP routing.

The relationships between these networks are generally described by one of the following three categories:

• Transit (or pay) – The network operator pays money (or settlement) to another network for Internet access (or transit).
• Peer (or swap) – Two networks exchange traffic between each other's customers freely, and for mutual benefit.
• Customer (or sell) – Another network pays a network money to provide them with Internet access.

Furthermore, in order for a network to reach any specific other network on the Internet, it must either:

• Sell transit (or Internet access) service to that network (making them a 'customer'),
• Peer directly with that network, or with a network who sells transit service to that network, or
• Pay another network for transit service, where that other network must in turn also sell, peer, or pay for access.

The Internet is based on the principle of global reachability (sometimes called end-to-end reachability), which means that any Internet user can reach any other Internet user as though they were on the same network. Therefore, any Internet connected network must by definition either pay another network for transit, or peer with every other network who also does not purchase transit.