Introduction to TCP/IP

Introduction to
TCP/IP
Michael Lamont
Chief Technology Officer

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

Basic Network Functionality
 BOS1 transmits data to BOS2
 BOS2 receives and interprets data from BOS1
 BOS2 transmits data back to BOS1
BOS1 BOS2

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

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

Application Data Flow
Application
Application Layer
Transport Layer
Internet Layer
Net Access Layer
Network
Application
Application Layer
Transport Layer
Internet Layer
Net Access Layer

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)

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

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

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

ARPAnet
 Dept of Defense grew
concerned that their
critical command-and-
control systems were
balkanized in late 1960s

ARPAnet
 DoD had small groups of
networked systems, but
they used proprietary
protocols
 Generally, only systems
from the same
manufacturer could be
networked together

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

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

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

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

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

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”

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

5 Core Networking Problems
 Addressing
 Routing
 Name resolution
 Flow control
 Interoperability

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

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

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

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

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

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

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

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

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

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

Name Resolution
 Name Resolution: the
process of mapping
logical addresses back
and forth into domain
names

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

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

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

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

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

 Internet Architecture
Board (IAB)
 Sets general policies for
the Internet
 Manages development of
data protocols and
standards

 Internet Engineering Task
Force (IETF)
 R&D organization that
develops Internet
standards
 Composed of working
groups that focus on a
particular area

 Internet Corporation for
Assigned Names and
Numbers (ICANN)
 Manages IP addresses,
domain names, and port
numbers

 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

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

Summary
 TCP/IP’s five key features:
• Logical addressing
• Routing
• Name resolution
• Flow control
• Simultaneous application support
 Internet standards and oversight bodies

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

Introduction to TCP/IP

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