How an ISP network works

This lesson explains how an ISP network operates and what happens when a user connects to the Internet. The connection first passes through the operator’s network—using access technologies such as DSL, FTTC, or FTTH—and then enters the ISP network via a Point of Presence (POP).

It introduces fundamental concepts such as the last mile, backbone, peering, Internet Exchange Points, and IP transit, illustrating how operators exchange traffic and reach external networks.

Finally, the lesson describes the ISP hierarchy—Tier 1, Tier 2, and Tier 3—distinguishing between local operators, regional providers, and the major global backbones that interconnect the Internet on an international scale.

Bibliography

Primary sources

Postel, J. (1981). Internet Protocol. RFC 791. IETF / RFC Editor.

Baker, F. (1995). Requirements for IP Version 4 Routers. RFC 1812. IETF / RFC Editor.

Hawkinson, J., & Bates, T. (1996). Guidelines for Creation, Selection, and Registration of an Autonomous System. RFC 1930. IETF / RFC Editor.

Rekhter, Y., Li, T., & Hares, S. (2006). A Border Gateway Protocol 4 (BGP-4). RFC 4271. IETF / RFC Editor.

Fuller, V., & Li, T. (2006). Classless Inter-domain Routing (CIDR): The Internet Address Assignment and Aggregation Plan. RFC 4632. IETF / RFC Editor.

Housley, R., Curran, J., Huston, G., & Conrad, D. (2013). The Internet Numbers Registry System. RFC 7020. IETF / RFC Editor.

ITU-T. Recommendation G.992.1 — Asymmetric Digital Subscriber Line (ADSL) Transceivers.

Broadband Forum. (2011). TR-101 Issue 2 — Migration to Ethernet-Based Broadband Aggregation.

ITU-T. Recommendation G.984.1 — Gigabit-capable Passive Optical Networks (GPON): General Characteristics.

ITU-T. Recommendation G.9807.1 — 10-Gigabit-capable Symmetric Passive Optical Network (XGS-PON).

RIPE NCC. Internet Exchange Point Tutorial.

Euro-IX. Internet eXchange Point Database / IXPDB.

PeeringDB. About PeeringDB.

CAIDA. AS Rank.

Secondary sources

Kurose, J. F., & Ross, K. W. Computer Networking: A Top-Down Approach. Pearson.

Tanenbaum, A. S., & Wetherall, D. J. Computer Networks. Pearson.

Comer, D. E. Computer Networks and Internets. Pearson.

Peterson, L. L., & Davie, B. S. Computer Networks: A Systems Approach. Morgan Kaufmann.

Stallings, W. Data and Computer Communications. Pearson.

Doyle, J., & Carroll, J. Routing TCP/IP, Volume I. Cisco Press.

Halabi, S., & McPherson, D. Internet Routing Architectures. Cisco Press.

Odom, W. CCNA 200-301 Official Cert Guide. Cisco Press.

Index

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