IST 201 - John Rouda

IST 201

Chapter 9

Lecture 1

TCP/IP Model

Application

Transport

Internet

Network Access

Application Layer Protocols

Application

Transport

Internet

Network Access

FTP

TFTP

NFS

SMTP

Telnet

Rlogin

SNMP

DNS

HTTP

Transport Layer Protocols

Application

Transport

Internet

Network Access


TCP

UDP


Internet Layer Protocols

Application

Transport

Internet

Network Access

IP

ICMP

ARP

RARP

Network Access

Application

Transport

Internet

Network Access

Ethernet

Fast Ethernet

SLIP & PPP

FDDI

ATM, Frame Relay, SMDS

ARP

Proxy ARP

RARP

TCP


Segments upper layer application data


Sends segments from one end device to
another


Establishes end to end operations


Flow control


Reliability
–

sequence #’s &
acknowledgements


Error detection & correction





Three
-
way Handshake

Has a
message to
send

Sending host/node

Receiving host/node

TCP three
-
way handshake to
establish a logical communication
connection. Communication can
begin once the handshake is
complete. A three
-
way
handshake is also used to end the
connection.

IP


Defines a packet & address scheme


Transfers data between Internet layer
and network access


Connectionless

Network Access


Software & drivers for NIC, ISDN &
modems


Mapping IP addresses to MAC
addresses


Encapsulating packets into frames


Defines the connection with the
medium

TCP/IP Model v. OSI



Application

Presentation

Session

Transport

Network

Data Link

Physical

Application

Transport

Internet

Network Access

TCP/IP & OSI Similarities


Layers


Packet switched

TCP/IP & OSI Differences


TCP/IP Model combines first three
layers of OSI


TCP/IP Model combines data link &
phys into network access


TCP/IP
–

simpler


TCP/IP
–

internet was built based on it


OSI
–

guide for understanding
communication process

Internet Architecture


Getting messages from one network to another
requires different approaches than getting messages
from one host to another on a LAN


Internetworking
–

building networks of networks


must be scalable
-

# networks & computers


transport data vast distances


flexible for technological changes


dynamic


cost effective


anytime, anywhere communication


IANA


Internet Assigned Numbers Authority


organization that assigns network addresses


duplicate public addresses not allowed


organizations may obtain IP network address
from an ISP for $


IP Addressing


IP address for each node must be unique


Four bytes (bytes called octets)


10.9.19.3 might be a node address


10.0.0.0 would be the network address


The first 10 in 10.9.19.3 corresponds to the network in this
example.


Subnet mask identifies which part of the IP address
refers to the network address and which part to the
node.


11111111.00000000.00000000.00000000 (binary subnet mask)


255.0.0.0 would be the subnet mask



Unique
address

IP Address Classes


Businesses are assigned network IP
addresses by IANA depending on the
size of the business.


Class A
–

very large businesses such as
the US government


Class B
–

large businesses


Class C
–

medium sized businesses

IP Class Addresses and Subnet
Masks


The first number of the network
address identifies the network class


Class A: 1
–

126


S/N mask: 255.0.0.0


Class B: 128
–

191


S/N mask: 255.255.0.0


Class C: 192
–

223


S/N mask: 255.255.255.0

127 used for
loopback address
(troubleshooting)

Private addresses


10.0.0.0


172.16.0.0


192.168.0.0


May only be used internally.

ICMP


Internet Control Message Protocol


Ping and Tracert are two utilities that
use ICMP.


Provides control and error messaging
capabilities.


Proposed Solutions to Too
Few IPv4 Network Addresses


CIDR (classless interdomain routing)


Single IP address can represent many IP
addresses


Example: 172.200.0.0/16


Private addressing internally


Using NAT (network address translation) to map
external public address to internal private
addresses


IPv6

Proxy ARP


If a host wants to communicate with a
host that is not in the same network,
the router can be configured to provide
it’s own MAC address if the destination
host address is not in the MAC table.


This process allows the message to
leave and re
-
enter the network via the
router.

Default Gateway


Configured router interface that is used
to communicate with hosts outside the
current segment (network).


Router sends it’s own MAC address.

Static v. DHCP Addresses


Static address
–

manually assigned by
the network administrator


DHCP
–

dynamic host configuration
protocol


Dynamically (automatically) assigns IP
addresses to hosts on the network for
some predetermined amount of time.