---
date: '2025-01-15'
description: and its origin.
id: Internet
modified: 2026-06-05 15:08:23 GMT-04:00
tags:
  - sfwr4c03
  - networking
title: Internet
created: '2025-01-15'
published: '2025-01-15'
pageLayout: default
slug: thoughts/Internet
permalink: https://aarnphm.xyz/thoughts/Internet.md
generator:
  quartz: v4.6.0
  hostedProvider: Cloudflare
  baseUrl: aarnphm.xyz
full: https://aarnphm.xyz/llms-full.txt
---
Hierarchical architecture

- Tier-1 ISP <span>&rarr;</span> Tier-2 ISP <span>&rarr;</span> Tier-3 ISP <span>&rarr;</span> Local ISP

```mermaid
graph TD
    T1A[Tier 1 ISP A]
    T1B[Tier 1 ISP B]

    T2A[Tier 2 ISP A]
    T2B[Tier 2 ISP B]

    T3A[Local ISP A]
    T3B[Local ISP B]

    T3A -->|transit| T2A
    T3B -->|transit| T2B
    T2A -->|transit| T1A
    T2B -->|transit| T1B

    T1A <-->|peering| T1B
    T2A <-->|peering| T2B

    classDef tier1 fill:#ff9999
    classDef tier2 fill:#99ff99
    classDef tier3 fill:#9999ff

    class T1A,T1B tier1
    class T2A,T2B tier2
    class T3A,T3B tier3
```

Use `traceroute` for finding probes between transit