Network Protocols

• We’ll look at IP, TCP and HTTP.

IP - Internet Protocol

• An IP packet consists of a header and data.

• The header contains (20 - 60 bytes):

  • The source IP address.
  • Destination IP address.
  • Size of packet
  • Version of the IP packet (IPv4, IPv6)

• The data contains:

  • The body can only be 2^16 bytes (65536 bytes)
  • IP does not guarantee that the server receives packets
  • or that packets are received in order.

TCP - Transmission Control Protocol

• Built on top of IP
• Packets are guaranteed to be in order, and all sent, or an error is sent back to client.
• This lets you send arbitrarily long packets of data.
• The TCP header takes up more of the data part of the IP packet.
• This contains information about the ordering of the packets.

TCP starts out with a handshake.

• the client sends the server a metadata packet
• the server sends one back
• the client says ok
• Connection opens.
• Connections can be timed out.

HTTP - HyperText Transfer Protocol

• HTTP is built on top of TCP.
• this creates a request - response paradigm or client - server model.
• an HTTP request has a host, port, method, headers, and a body.
• responses have a status code, headers, and a body.

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