Tier 4:
- most datacenters
- owns internal network
- pay other networks for IP transit outside the facility
Tier 3:
- regional providers
- build redundancy thru’ redundant POPs (points of presence) outside facility
- pay for IP transit past the POPs
Tier 2:
- national or international footprint
- still pay IP transit to reach some portions of Internet
Tier 1:
- do not pay IP transit
- global presence
- don’t pay other providers for any portion of connectivity
