Lesson 13 University of the Cumberlands Professor: Dr. Irvin R. Heard Course: ISOL 634 Physical Security (20-21) Reading AssignmentChapter 17 Individual Project 13 Identify and discuss the seven layers of the Open System Interconnection (OSI) model and their importance on TCP/IP operation. Minimum two pages. Helpful topics to research:OSI LayersHow TCP/IP WorksTCP/IP Operates on Open Systems Interconnection Levels 3 (IP) and 4 (TCP) TCP/UDP/RTP User Datagram Protocol TCP/IP Address Schemes Open Systems Interconnection (OSI) Reference ModelLayer 7--Application layerLayer 6--Presentation layerLayer 5--Session layerLayer 4--Transport layerLayer 3--Network layerLayer 2--Data Link layerLayer 1--Physical layer OSI – Upper and Lower LevelsThe seven layers of the OSI reference model can be divided into two categories: upper layers and lower layers.The upper layers of the OSI model deal with application issues and generally are implemented only in software. The highest layer, application, is closest to the end user. Both users and application-layer processes interact with software applications that contain a communications component. The term upper layer is sometimes used to refer to any layer above another layer in the OSI model.The lower layers of the OSI model handle data transport issues. The physical layer and data-link layer are implemented in hardware and software. The other lower layers generally are implemented only in software. The lowest layer, the physical layer, is closest to the physical network medium (the network cabling, for example, and is responsible for actually placing information on the medium. TCP/IP The networking industry uses the OSI seven layer model as a standard, however before that was a standards TCP/IP was being developed (OSI was just completed first and adopted). Both models have similar goals. Its often to see developers apply OSI terminology to TCP/IP. Similarities The most compatible aspects at the Transport and Internet layers (called the Network in OSI) TCP/UDP/RTP Click the titles to review resourcesTransportation Protocols: UDP,TCP & RTPTeach Yourself TCP/IP in 24 hrs (Book) TCP/IP Address SchemesTCP/IP includes an Internet addressing scheme that allows users and applications to identify a specific network or host to communicate with. An Internet address works like a postal address, allowing data to be routed to the chosen destination. TCP/IP provides standards for assigning addresses to networks, subnetworks, hosts, and sockets, and for using special addresses for broadcasts and local loopback. Internet addresses are made up of a network address and a host (or local) address. This two-part address allows a sender to specify the network as well as a specific host on the network. A unique, official network address is assigned to each network when it connects to other Internet networks. However, if a local network is not going to connect to other Internet networks, it can be assigned any ...

1. Lesson 13
University of the Cumberlands
Professor: Dr. Irvin R. Heard
Course: ISOL 634 Physical Security (20-21)
Reading AssignmentChapter 17
Individual Project 13
Identify and discuss the seven layers of the Open System
Interconnection (OSI) model and their importance on TCP/IP
operation.
Minimum two pages.
Helpful topics to research:OSI LayersHow TCP/IP
WorksTCP/IP Operates on Open Systems Interconnection
Levels 3 (IP) and 4 (TCP) TCP/UDP/RTP User Datagram
Protocol TCP/IP Address Schemes
Open Systems Interconnection (OSI) Reference ModelLayer 7--
Application layerLayer 6--Presentation layerLayer 5--Session
layerLayer 4--Transport layerLayer 3--Network layerLayer 2--
Data Link layerLayer 1--Physical layer

2. OSI – Upper and Lower LevelsThe seven layers of the OSI
reference model can be divided into two categories: upper
layers and lower layers.The upper layers of the OSI model deal
with application issues and generally are implemented only in
software. The highest layer, application, is closest to the end
user. Both users and application-layer processes interact with
software applications that contain a communications
component. The term upper layer is sometimes used to refer to
any layer above another layer in the OSI model.The lower
layers of the OSI model handle data transport issues. The
physical layer and data-link layer are implemented in hardware
and software. The other lower layers generally are implemented
only in software. The lowest layer, the physical layer, is closest
to the physical network medium (the network cabling, for
example, and is responsible for actually placing information on
the medium.
TCP/IP
The networking industry uses the OSI seven layer model as a
standard, however before that was a standards TCP/IP was being
developed (OSI was just completed first and adopted). Both
models have similar goals. Its often to see developers apply OSI
terminology to TCP/IP.
Similarities
The most compatible aspects at the Transport and Internet
layers (called the Network in OSI)

3. TCP/UDP/RTP
Click the titles to review resourcesTransportation Protocols:
UDP,TCP & RTPTeach Yourself TCP/IP in 24 hrs (Book)
TCP/IP Address SchemesTCP/IP includes an Internet addressing
scheme that allows users and applications to identify a specific
network or host to communicate with. An Internet address
works like a postal address, allowing data to be routed to the
chosen destination. TCP/IP provides standards for assigning
addresses to networks, subnetworks, hosts, and sockets, and for
using special addresses for broadcasts and local loopback.
Internet addresses are made up of a network address and a host
(or local) address. This two-part address allows a sender to
specify the network as well as a specific host on the network. A
unique, official network address is assigned to each network
when it connects to other Internet networks. However, if a local
network is not going to connect to other Internet networks, it
can be assigned any network address that is convenient for local
use.
Internet Address
Internet Addresses
The Internet Protocol (IP) uses a 32-bit, two-part address field.
The 32 bits are divided into four sections or octets as in the
following:
01111101 00001101 01001001 00001111
These binary numbers translate into:
125 13 73 15
The two parts of an Internet address are the network address
portion and the host address portion. This allows a remote host

4. to specify both the remote network and the host on the remote
network when sending information. By convention, a host
number of 0 (zero) is used to refer to the network itself.
TCP/IP supports three classes of Internet addresses: Class A,
Class B, and Class C. The different classes of Internet addresses
are designated by how the 32 bits of the address are allocated.
The particular address class a network is assigned depends on
the size of the network.
Class A
Class A Addresses
A Class A address consists of an 8-bit network address and a
24-bit local or host address. The first bit in the network address
is dedicated to indicating the network class, leaving 7 bits for
the actual network address. Since the highest number that 7 bits
can represent in binary is 128, there are 128 possible Class A
network addresses. Of the 128 possible network addresses, two
are reserved for special cases: the network address 127 is
reserved for local loopback addresses, and a network address of
all ones indicates a broadcast address.
Therefore, there are 126 possible Class A network addresses and
16,777,216 possible local host addresses. In a Class A address
the highest order bit is set to 0.
In other words, the first octet of a Class A address is in the
range 1 to 126.
*
Class B
Class B Addresses

5. A Class B address consists of a 16-bit network address and a
16-bit local or host address. The first two bits in the network
address are dedicated to indicating the network class, leaving 14
bits for the actual network address. Therefore, there are 16,384
possible network addresses and 65,536 local host addresses. In a
Class B address the highest order bits are set to 1 and 0.
In other words, the first octet of a Class B address is in the
range 128 to 191.
Class C
Class C Addresses
A Class C address consists of a 24-bit network address and an
8-bit local host address. The first two bits in the network
address are dedicated to indicating the network class, leaving 22
bits for the actual network address. Therefore, there are
2,097,152 possible network addresses and 256 possible local
host addresses. In a Class C address the highest order bits are
set to 1 and 1.
In other words, the first octet of a Class C address is in the
range 192 to 223.
When deciding which network address class to use, you need to
consider how many local hosts there will be on the network and
how many subnetworks there will be in the organization. If the
organization is small and the network will have fewer than 256
hosts, a Class C address is probably sufficient. If the
organization is large, then a Class B or Class A address may be
more appropriate.

6. Discussion Board 13
How can the OSI Seven-Layer Network Model be applied to
Information Security?
Helpful Resource
Questions
?