Yeh explain kiya jaa raha hai neeche:

Tier-1 ISP: Yeh ISPs hierarchy mein sabse upar hote hain aur inka global reach hota hai. Yeh apne network se kisi bhi internet traffic ke liye paise nahi dete, balki lower-tier ISPs ko apne traffic ko ek location se doosri location tak bhejne ke liye paise dene padte hain, jo unke reach ke bahar hota hai. Aksar, same level ke ISPs ek dusre se connect hote hain aur free traffic ek dusre ko pass karte hain. In ISPs ko peers kaha jaata hai. Isse cost bachti hai. Yeh apna infrastructure bhi banate hain, jaise Atlantic Internet sea cables, jo doosre Internet service providers ko traffic provide karte hain, end users ko nahi. Examples:
Kuch tier-1 Internet providers ke examples:

• • Cogent Communications
  • Hibernia Networks
  • AT&T

Tier-2 ISP: Yeh ISPs tier 1 aur tier 3 ISPs ke beech connect karte hain. Inka regional ya country level reach hota hai aur yeh tier-3 ISPs ke liye tier-1 ISP jaise behave karte hain.
Examples:
Tier-2 ISPs ke examples:

• • Vodafone
  • Easynet
  • BT

Tier-3 ISP: Yeh ISPs end users ke sabse kareeb hote hain aur unhe internet se connect karne mein madad karte hain, lekin yeh paise charge karte hain. Yeh ISPs purchasing model par kaam karte hain. Yeh tier-2 ISPs ko kuch cost dete hain, jo traffic generate hota hai uske basis par.
Examples:
Tier-3 ISPs ke examples:

• • Comcast
  • Deutsche Telekom
  • Verizon Communications