Internet Operation

How the internet works #

Base level: protocol stack, e.g.

(application)---datagram socket--->(user datagram protocol impl)---payload--->(internet datagram protocol impl)
--->(IP)--->(UDP)---datagram socket--->(application server)

Note not all of these are visible, because of encapsulation!

What users and applications want #

  • Reliable retrieval of a short piece of data

    • e.g. IP address lookup for saligrama.io

  • Reliable action

    • Text of 7th message is “Fire a torpedo”

  • Reliable byte stream

    • Sequence of bytes in each direction delivered in order, correctly

  • Reliable delivery of a large file (FTP, SMTP, HTTP)

  • Reliable remote procedure call (e.g., HTTP/1, HTTP/2, HTTP/3, gRPC, Thrift)

  • “Request-response abstraction” – build on top of user datagrams

    • Idempotency of requests: some requests always create the same response (e.g. HTTP GET)

Dynamic Host Configuration Protocol (DHCP) #

  • Over UDP port 67
  • For a host to request an IPv4 address

Domain Name System (DNS) #

See CS249I notes.