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.
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