Tiered Networks
We'll draw something like the following to draw out these Autonomous Systems (AS, Networking)'s:
PoP (Point of Presence)
A point of presence is just usually a smaller IXP. Usually they are more local; say they may be some random point in SLO that would connect to the larger ISP that supplies internet to SLO.
We sometimes divide networks into tiers:
- Tier 1 networks are the largest networks (geographically; global reach)
- Peer with other Tier 1's typically do not pay (since they have the largest connections)
- Backbone of the Internet
- They have their own infrastructure (undersea cables, cross country connections)
- Ex: AT&T, Verizon, Lumen Technologies (Century Link), Level 3 Communications, ...
- Tier 2 networks are usually used for larger ISP (Internet Service Provider)s.
- Are more regional and pay Teir 1 providers for connections
- Peer with other Tier 2's in the local/regional scope
- Doesn't have the global reach of a Tier 1
- Ex: Cox, Comcast, Charter Communications, China Telecom, ...
- Tier 3 networks are usually mutli-homed or single homed ISPs.
- ...
"The Last Mile"
Here the last mile refers to how the cables right from customers/houses usually hit a Tier 3 network (often hitting some repeater or whatnot before getting to the actual network hardware).