IST 201 - John Rouda

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30 Οκτ 2013 (πριν από 3 χρόνια και 9 μήνες)

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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.