Transit IP And Peering, The Basis Of Internet Service
Transit IP And Peering
Telecom operators have two interconnection services allowing their networks to connect directly and indirectly to the Internet: Peering and transit. If these two terms meet the same need to facilitate Internet traffic, they are different in appearance.
The Internet is a set of interconnected networks. These networks use common protocols for exchanging information. These large networks include internet servers that act as central repositories of information and other servers that take care of routing that information. The routers will ensure that the devices installed on these networks can communicate with each other.
When a network router receives a request, it queries its routing table to determine the shortest path to route the information. This will first look at its own network to determine if the destination is there. If this is not the case, a “gateway” router will take care of getting the request out of the network.
Leaving its own network, the request will have to find its way through the Internet. The Internet is made up of a hierarchical stack of networks.
- Higher-level networks, Internet backbone: The Internet backbone or backbone results from the interconnection of fibre optic networks and broadband from telecom operators. By grouping, these network operators will set up a global network including all the routing tables of the global Internet (AT&T, Orange, Cogent, etc.)
- Next, come smaller networks. At the very bottom of these strata are operators, often the ISPs with which consumers and businesses subscribe, who cannot directly access the backbone. In theory, their traffic would be limited to their own network. To solve this problem, intermediate networks will establish a link between the networks of higher levels and those lower.
These interconnections allow networks, limited in size, to convey information anywhere in the world. However, these interconnections will take place in several ways.
What Is Peering?
These networks of different sizes will therefore bind to each other. These can form direct links with each other. Each gives the other access to the routing tables of its network to facilitate the routing of information. However, this agreement will only work for networks, and operators, of similar size. Low-level networks cannot set up such an exchange with higher-level actors.
National operators (like French ISPs) can also deploy large national or even international networks by multiplying peering agreements. However, they cannot guarantee global Internet access to their customers without access to the backbone.
What Is IP Transit?
Peering is, therefore, sometimes not enough to route a packet from point A to point B. Indeed, there is an asymmetry between the networks of the various telecom players. A financial agreement is then established so that an operator can access a more extensive network, and the latter is named forwarder.
Therefore, when a company wishes to send or receive information over the Internet, it must “transit” through one or more third-party networks to reach its final destination. The company will often deal with an ISP located at the bottom of the network scale. And this ISP will forge links with other operators to offer a complete internet access service.
Under these conditions, the quality of service offered by an operator will be correlated to the number of interconnections established with other networks.
Tiers Of IP Transit Providers
IP transit providers are divided into three tiers. These follow the levels of the different backbones that make up the Internet:
Level 1 Operators (Tier 1)
Tier 1 providers have an extensive global reach. These providers connect to each other to form the “backbone” of the Internet. Tier 1 providers trade freely with each other but charge players below to give them access to their network. The combination of these Tier 1 providers forms a set of extended routing tables capable of routing requests anywhere on the Internet.
Level 2 Operators (Tier 2)
Tier 2 providers have large networks with multiple physical locations and data centres. These players will generally trade freely with each other in order to expand their capacity to deliver content and avoid the usage costs associated with access to a Tier 1 network.
Level 3 Operators (Tier 3)
Tier 3 vendors are typically local vendors with smaller customer lists. They will normally purchase a smaller portion of IP transit through a Tier 2 provider to avoid the higher costs of going directly to a Tier 1 ISP.
What Is The Difference Between Transit And Peering
No network is big enough to connect every person and every computer, and transit and Peering take care of this interconnection. Transit and Peering will therefore determine how traffic flows on the Internet.
The monetary aspect constitutes the significant difference between these two methods. Indeed, Peering is used by networks of the same value, even if a financial agreement can sometimes settle the differences. Transit necessarily involves a transaction since it is a traffic agreement between two networks whose intrinsic value differs.