Definition

Peering is a method that allows two networks to connect and exchange traffic directly without having to pay a third party to carry traffic across the Internet.

Overview

The Internet consists of over 25,000 autonomous systems that independently route traffic. Peering is often used as a method by which these systems can interact and exchange traffic, allowing it to flow from one end user, over the Internet, to another end user.

This method is a necessity for interconnected companies, Internet service providers (ISPs), content delivery networks (CDNs), and backbone service providers. Forming peering agreements with other networks and avoiding third-party involvement allows companies to:

  • Lower transit costs
  • Retain greater control of routing paths
  • Improve overall network performance
  • Increase redundancy by using multiple locations
  • Increase bandwidth capacity
  • Have access to additional support provided by peering partners

Types of peering connections

Peering indicates that two networks connect, but it does not indicate how they are connected. The process could be initiated by running a circuit from one facility to another, but that method becomes inefficient when a network requires multiple peers. Two more common and efficient types of peering are called public peering and private peering.

Public peering

Public peering is generally done through an Internet exchange point (IXP). At these locations, one network can peer with multiple other networks. Peering arrangements need to be negotiated with each peer, but no new cabling needs to be done.

Private peering

Private peering takes place in a colocation facility where two entities with separate networks place routers and run a direct cable between them, rather than using an exchange point switch. This method is useful when networks need to exchange a mass amount of traffic that is unable to fit on a shared connection at an exchange point.

How Peering Works

An Internet exchange point provides a single location for all the hardware necessary to connect multiple networks. Internet exchange providers have membership forms on their websites that you can fill out to apply for space at their colocation. If you are approved, they will contact you directly to facilitate your physical connection to their colocation.

Having a physical connection to an IXP does not mean you automatically have peering agreements with any other network there. Each network that is willing to enter into peering agreements at these locations usually has operational and technical requirements that you must meet before being able to connect to them. Most ISP peering agreements require that you have the following:

  • A publicly routed ASN
  • At least one block of public IP addresses
  • A network edge router capable of running BGP

Once you’ve been approved to peer with a network, you have to manually configure your router’s peering settings to talk to a specific ASN using Border Gateway Protocol (BGP).

Peering at the edge

Edge computing environments operate successfully by having high throughput, fast speeds, and low prices. Without peering, edge computing would likely be impossible. More peering partners means faster edge computing and faster content delivery. StackPath, for example, has over 2,600 peering partners all over the world, including Verizon, Cogent, and CenturyLink/Level3, and their points of presence (PoPs) can transfer over 65 terabytes per second combined.

Examples of Peering

DE-CIX is one of the largest Internet exchanges in the world. They have over 1,600 connected ASNs and can move almost 50 terabytes of traffic per second through their 18 locations.

One of the perks of working with an Internet exchange like DE-CIX is that they will often have multilateral agreements in place, meaning that their requirements to be a member match most of their customers’ requirements to peer. When you are approved for a connection to one of DE-CIX’s colocations, you are connected to a route server that gives you instant access to 80% of connected networks.

Netflix Open Connect

In 2015, Sandvine reported that Netflix is the source of 37% of all Internet traffic in North America. Few content delivery networks can match the outbound traffic flow that Netflix produces or meet its minimal latency requirements.

To facilitate their need for hundreds of peering locations, Netflix provides Open Connect Appliances (OCAs) for free to Internet service providers meeting their requirements. Each OCA is designed for the highest level of availability, coming with redundant system drives, power supplies, and network interface ports.

Key Takeaways

  • Public and private peering allows two networks to connect at a colocation and exchange traffic directly without having to pay a third party to carry traffic across the Internet.
  • To enter into a peering agreement with most Internet service providers, you must have at least a publicly routed ASN, one block of public IP addresses, and a network edge router capable of running Border Gateway Protocol.

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