Transcript Computer Networks

Peer-to-Peer vs. Client/Server
Network Operating Systems
Instructor: Dr. Najla Al-Nabhan
2015
1
Peer-to-peer vs. server-based networks
A
network is either:
a peer-to-peer network (also called a
workgroup) or
 a server-based network (also called a
client/server network).

Peer-to-peer based NW
2
Client/Server based NW
Peer-to-peer networks
In a peer-to-peer network, a group of computers is
connected together so that users can share resources
and information.
In most peer-to-peer networks, it is difficult for users
to track where information is located because data is
generally stored on multiple computers.
This makes it difficult to back up critical business
information, and it often results in small businesses
not completing backups.
Often, there are multiple versions of the same file on
different computers in the workgroup.




3
Peer-to-peer networks

In some peer-to-peer networks, the small
business uses one computer that is running a
client operating system, such as Microsoft
Windows 98 or Windows XP Professional, as
the designated "server" for the network.

Although this helps with saving data in a
central location, it does not provide a robust
solution for many of the needs of a small
business, such as collaborating on documents.
4
Client/Server Networks
In a server-based network, the server is the
central location where users share and access
network resources .
 This server controls the level of access that
users have to shared resources.
 Shared resources are in one location, making
it easy to back up critical business information.
 Each computer that connects to the network
is called a client computer.

5
Client/Server Networks

In a server-based network, users have one user
account and password to log on to the server and
to access shared resources.

Server operating systems are designed to handle
the load when multiple client computers access
server-based resources.
6
Client/Server Networks
A Server OS is installed and configured as the
central server on a server-based network mainly
to provide:
1. the central point for authenticating users,
2. accessing resources, and
3. storing information.

7
Peer-to-peer NOS
Computers in peer-to-peer networks are usually
equipped with a desktop operating system in order to
allow them to create and share resources with each
other.
All computers are considered equal because they have
the same capabilities including : routing and management
functions.
Two well-known NOS :





8
Windows for workgroup/windows 95
Appleshre
Peer-to-peer NOS

The range of features offered by peer-to-peer
NOS is limited when compared to server
NOS.

They usually offer file sharing and printing as
basic features

For small networks
9
Peer-to-peer NOS: Advantages and
disadvantages
10
Windows for Workgroups/Windows 95




Windows for Workgroups, introduced in the early
90s
Windows 95, introduced in 1995
They are both considered peer-to-peer networking
systems and do not have the capabilities of true
internetworking operating systems.
They are, however, inexpensive and more than
adequate for small workgroups wanting to share
resources, use email, and connect to the Internet.
11
Windows for Workgroups/Windows 95
Windows for Workgroups and Windows 95
both offer peer-to-peer network protocols.
 The protocols used by these operating
systems allow users to share files and devices
over LANs.
 Both offer NetBEUI (Microsoft’s small network
protocol).
 They also offer TCP/IP, and IPX/SPX protocols
to access the network through either a dialup
connection/modem, or directly through a NIC.

12
NetBEUI features
Pronounced net-booey, NetBEUI is short
for NetBios Extended User Interface.
 It is an enhanced version of
the NetBIOS protocol used by network
operating systems such as:



LAN Manager, LAN Server, Windows for
Workgroups,Windows 95 and Windows NT.
Netbeui was originally designed by IBM for
their Lan Manager server and later extended
by Microsoft and Novell.
13
NetBEUI features

NetBEUI protocols, are :



not routable,
more than adequate to meet small LAN needs.
easy to use and do not require in-depth networking
knowledge.


NetBEUI software identifies computer devices
by name it is easier to remember that a
computer name is Nora than 141.252.20.2 or
141.252.10.1.
14
Windows for Workgroups/Windows 95




Each device name in a network must be unique.
NetBEUI software installed on each of the networked
computers is all that is necessary to configure devices in
order to share resources and create a network.
If a small company does want to connect to the
Internet, the necessary software and protocols are
available with these operating systems.
Shared resources on Windows for Workgroups/95
networks are accessed by a password that protects the
resource and there is only one level of access; either
you have access or you don’t have access.
15
Windows for Workgroups/Windows
95: Security Issues



Also user-by-user passwords are not part of the
protocols unless Windows NT is present.
What this means is that anyone connected to the
network who knows the password of the resource has
access to that resource.
This can create security issues since there is no way to
prevent a user from access once s/he knows the
password.
16
Windows for Workgroups/Windows
95:Security Issues


As the network grows, it is usually more difficult to keep
resource passwords secure.
Since there is no central control, managing these peer-topeer networks becomes an issue when the network
becomes too large.
17
Windows for Workgroups/Windows
95:Security Issues

To be continued next lecture…
18