Chapter 2. Delivering the Data
Chapter 1 touched on the basic architecture and design of the TCP/IP protocols. From that discussion, we know that TCP/IP is a hierarchy of four layers. This chapter explores in finer detail how data moves between the protocol layers and the systems on the network. We examine the structure of Internet addresses, including how addresses route data to its final destination and how address structure is locally redefined to create subnets. We also look at the protocol and port numbers used to deliver data to the correct applications. These additional details move us from an overview of TCP/IP to the specific implementation details that affect your system’s configuration.
Addressing, Routing, and Multiplexing
To deliver data between two Internet hosts, it is necessary to move the data across the network to the correct host, and within that host to the correct application or process. TCP/IP uses three schemes to accomplish these tasks:
- Addressing
IP addresses, which uniquely identify every host on the network, deliver data to the correct host.
- Routing
Gateways deliver data to the correct network.
- Multiplexing
Protocol and port numbers deliver data to the correct software module within the host.
Each of these functions—addressing between hosts, routing between networks, and multiplexing between layers—is necessary to send data between two cooperating applications across the Internet. Let’s examine each of these functions in detail.
The IP Address
An IPv4 address is ...
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
and much more.
Read now
Unlock full access