Backbone

Tier 1 Nets

• Reach all other networks without paying
  • Settlement-free interconnection
• Tier 2 & 3 pay for interconnects
• Examples
  • AT&T
  • Orange
  • Verizon Enterprise

Regional Tier 1

• Aren’t globally transit-free
  • But tier 1 within a specific region

Tier 2 Nets

• Pays for some transit
  • Doesn’t for others
• Borderline Tier 1
  • RETN
  • Vodafone Carrier
  • Comcast

Tier 3 Nets

• Pays for all transit

Hyperscalers

• Challenges tier system
  • Built their own backbones
• Aren’t typically considered Tier 1
  • They are transit-free
  • Primary purpose not to sell transit
  • Separate category