TCP/IP is a set of protocols that defines how data is transmitted and formatted so that networked systems can communicate. It originated from ARPAnet, which was developed by the Department of Defense to create a decentralized network resilient to attacks. TCP/IP provides logical addressing, routing between networks, name resolution from names to addresses, error checking and flow control for reliable data transmission, and support for multiple applications simultaneously through the use of ports. It is overseen by various standards organizations to ensure interoperability.
2. Introduction
TCP/IP is a set of data transfer protocols used by
modern data networks
Data network: a group of computers and other devices
that communicate over a shared medium
Data & requests for data are transmitted between
computers over the network
Physical transmission mediums can be copper cables,
fiber optics, or radio waves
3. Basic Network Functionality
BOS1 transmits data to BOS2
BOS2 receives and interprets data from BOS1
BOS2 transmits data back to BOS1
BOS1 BOS2
4. Applications
An application lets a computer interact with other
computers by performing a specific set of tasks
The application is responsible for managing the
transmitting and receiving of data required to perform
its tasks
The application has to be able to communicate with
applications on other networked computers for it to be
useful
6. Application Data Flow
Application
Application Layer
Transport Layer
Internet Layer
Net Access Layer
Network
Application
Application Layer
Transport Layer
Internet Layer
Net Access Layer
7. Applications
A network protocol is a set of rules for how
applications intercommunicate
Common applications include:
• SMTP, IMAP, and POP (email)
• HTTP (web)
• SSH (secure access)
• NFS and FTP (file transfer)
8. TCP/IP
The protocols that make up TCP/IP define:
• How data is transmitted across a network
• How data should be formatted so other networked systems
can understand it
TCP/IP provides a complete system for formatting,
transmitting, and receiving data on a network
9. TCP/IP
A TCP/IP implementation is a software package that
handles all of the formatting, transmitting, and
receiving of data
Process Software’s MultiNet and TCPware packages let
OpenVMS systems participate in data networks
10. The Internet
TCP/IP is the standard for modern data
communications across all networks
In the 1970s, two kinds of networks were being
developed:
• Local area networks (LANs)
• ARPAnet
11. ARPAnet
Dept of Defense grew
concerned that their
critical command-and-
control systems were
balkanized in late 1960s
12. ARPAnet
DoD had small groups of
networked systems, but
they used proprietary
protocols
Generally, only systems
from the same
manufacturer could be
networked together
13. ARPAnet
As the DoD became more reliant on computers, they
desperately needed everything on one big network
DoD knew this network would be a primary target for
the Soviets
Key requirement: the network had to be decentralized,
with no single point of failure
The network had to stay up in the face of a large-scale
nuclear attack
14. ARPAnet
Defense’s Advanced
Research Projects Agency
(ARPA) was tasked to
design and build this new
style of network
ARPAnet’s protocols
provided the basis for
TCP/IP
15. The Internet
In mid-1970s National Science Foundation wanted to
network universities and research institutions
NSF built off of ARPAnet’s design and protocols to
create the Internet
16. Decentralized Data Networking
TCP/IP’s decentralized nature is a key reason it’s still
ubiquitous today
Two key TCP/IP features support decentralization:
• End node verification: the two endpoints of any data transfer
are responsible for making sure it was successful – no
centralized control scheme
• Dynamic routing: End nodes can transfer data over multiple
paths, and the network chooses the best (fastest, most
reliable) path for each individual data transfer
17. Local Area Networks
LAN technology was being developed in parallel to
ARPAnet and the Internet
Early LANs were highly proprietary and didn’t support
the concept of a larger network (like the Internet)
Vendor lock-in was rampant
18. Local Area Networks
The wide adoption of open interconnectivity protocols
in the R&D community spilled over into corporations
TCP/IP was a proven solution that could make a
company’s disparate systems/networks all work
together
Growing popularity of the Internet also spilled over
into corporations
Email was the original “killer app”
19. Local Area Networks
Some LAN vendors started with a step in the right
direction: gateways between their proprietary
protocols and TCP/IP
Any LAN technology that survives today provides native
TCP/IP support
20. 5 Core Networking Problems
Addressing
Routing
Name resolution
Flow control
Interoperability
21. Physical Addressing
Every network-connected
hardware device has a
unique ID
This physical ID is
“burned” into the device
when it’s fabricated
Physical
Address
22. Physical Addressing
Guaranteed to be unique from the beginning to the
end of the Internet’s existence
Referred to as a MAC (Machine Access Code)
Low-level TCP/IP protocols use MAC addresses to move
data across the physical network to the right device
23. Physical Addressing
You can think of MAC addresses like phone numbers
On very small networks, nodes can just blindly dump
data onto the physical network
Every node has to examine every transmission and
figure out which data is meant for it
24. Physical Addressing
“Dump and parse” quickly exceeds hardware
capabilities as network size increases
Trying that scheme on the Internet would exceed
physics-imposed limits
Most addressing schemes that work with physical
addresses can’t scale beyond very small networks
25. Logical Addressing
Routers are special network devices that let you divide
large networks into smaller subnets
A well-designed network uses routers to create a tree-
like structure
The hierarchy of routers lets data travel between
nodes without hitting every other node on the network
26. Logical Addressing
TCP/IP provides native support for logical addressing
IP Address: logical address configured in a node’s
TCP/IP implementation
IP addresses can be broken down into network, subnet,
and host ID numbers:
143.192. 168. 227
27. Routing
Routers are specialized devices that move data across
networks
Routers use the logical address information in a data
packet to send it to its destination
Routers isolate a subnet’s traffic from the entire
network
Data transmitted between systems on the same subnet
isn’t transmitted across the larger network
28. Routing
Keeps unnecessary traffic
from cluttering up the
entire network
Data traffic destined for a
system outside the
subnet is transmitted as
far up the network as it
needs to go
Larger
Network
29. Routing
Large networks have lots
of routers and multiple
possible paths between
nodes
TCP/IP specifies how
routers should pick the
best path across a
network
RoutersRouters
30. Name Resolution
Logical IP addresses are “friendlier” than physical MAC
addresses, but still aren’t really human readable
Domain Names: structured, user friendly system
names provided by TCP/IP
Examples of domain names:
• www.process.com
• mail.wku.edu
• travel.state.gov
31. Name Resolution
Name Resolution: the
process of mapping
logical addresses back
and forth into domain
names
32. Name Resolution
Special name servers store the mapping information in
databases
TCP/IP’s Domain Name Service (DNS) provides a
hierarchy of name servers that handle name resolution
for the Internet
33. Error Checking & Flow Control
Several features integrated into TCP/IP guarantee
reliable data transfers:
• All data transmissions are checked for corruption and missing
data
• All data transmissions are positively acknowledged by the
receiving node
• In-band flow control so any system involved in a data
transmission can control the rate at which data is sent
34. Application Support
Key feature of modern networks is ability to run
multiple network apps simultaneously
Ports: logical channels provided by TCP/IP that allow
multiple applications to access the network
simultaneously
Ports identified by unique numbers
36. Standards Organizations
TCP/IP is based on open and complete standards
Standards guarantee interoperability of network
software and hardware
Several standards organizations are responsible for
developing and maintaining TCP/IP’s standards
37. Standards Organizations
Internet Architecture
Board (IAB)
Sets general policies for
the Internet
Manages development of
data protocols and
standards
38. Standards Organizations
Internet Engineering Task
Force (IETF)
R&D organization that
develops Internet
standards
Composed of working
groups that focus on a
particular area
39. Standards Organizations
Internet Corporation for
Assigned Names and
Numbers (ICANN)
Manages IP addresses,
domain names, and port
numbers
40. Standards Organizations
Requests for Comments (RFC): standards published by
the IETF
Every part of TCP/IP and the Internet has its own RFC
RFCs are the best way to get a complete understanding
of a standard, protocol, or practice
Freely available from www.ietf.org
41. Summary
Networking and protocol basics
The TCP/IP protocol family originated from the US
Department of Defense’s ARPAnet
ARPAnet’s resilient design architecture has been
carried forward to the Internet
TCP/IP is a completely decentralized protocol that’s
device agnostic
42. Summary
TCP/IP’s five key features:
• Logical addressing
• Routing
• Name resolution
• Flow control
• Simultaneous application support
Internet standards and oversight bodies