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.

1. Introduction to
TCP/IP
Michael Lamont
Chief Technology Officer

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

5. Applications
 A network protocol is a set of rules for how
applications intercommunicate

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

35. Ports
App
TCP
Internet Layer
Net Access Layer
Network
UDP
App
App
App
App
Ports

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

43. www.process.com
(800) 722-7770
info@process.com