Internet diagram

                                                         




                                INTERNET

                        |
          --------------------------------
          |              |              |
       ISP-A          ISP-B          ISP-C
          |              |              |
          --------------------------------
                        |
                 +-------------+
                 | Global BGP  |
                 +-------------+
                        |
              -------------------
              |                 |
      Data Center A      Data Center B
              |                 |
         Web Servers      DNS Servers
              |
         www.google.com

From Your Home to the Internet

Laptop/PC
    |
    | 192.168.1.10
    |
Home Router
(Default Gateway)
192.168.1.1
    |
    | Public IP
    |
ISP Edge Router
    |
ISP Core Network
(OSPF )
    |
ISP Border Router
(BGP)
    |
Internet
    |
Google Data Center
    |
Google Server

Packet Flow Example

When you open Google:

PC
 ↓
Home Router
 ↓
ISP Edge Router
 ↓
ISP Core Router
 ↓
ISP Border Router
 ↓
Internet Backbone
 ↓
Google Border Router
 ↓
Google Data Center
 ↓
Google Web Server

Routing Protocols Involved

Your LAN            → No routing protocol needed
Home Router         → Default Route
ISP Internal        → OSPF / IS-IS
ISP to ISP          → BGP
Google Data Center  → BGP + EVPN/VXLAN

Big Picture

User LAN
    ↓
Home Router
    ↓
ISP
    ↓
Internet Backbone
    ↓
Cloud/Data Center
    ↓
Website Server

------------------------------------------------------------------------------------

ISP Networking 

                 Internet
                    |
             Border Router
                  (BGP)
                    |
             Core Routers
                 (OSPF)
                    |
        +-------------------+
        |                   |
       Edge Router         Edge Router
        |                   |
       Enterprise         Home Users
       Customers          Customers

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