Local Area Network (LAN) Design and Implementation

Local Area Network
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Contents
Task 1..........................................................................................................................................................3
A.C 1.1 critically evaluate different LAN technologies.............................................................................3
The different types of networks..........................................................................................................3
The architecture of local networks......................................................................................................3
A.C 1.2 critically analyse traffic intensive services and their performance..............................................5
A.C 1.3 Discuss LAN concerns and make recommendations to sustain network security, reliability and
performance............................................................................................................................................7
Task 2..........................................................................................................................................................9
A.C 2.1 design a LAN infrastructure for the company which will facilitate all of their requirements......9
Design of network: concepts...............................................................................................................9
A.C 2.2 critically evaluate the suitability of LAN components................................................................11
Task 3........................................................................................................................................................14
A.C 3.1 build and configure a LAN.........................................................................................................14
AC 3.2 Network security and configuration...........................................................................................16
Task 4........................................................................................................................................................27
A.C 4.1 critically discuss how this LAN infrastructure will be monitored and managed........................27
A.C 4.2 resolve LAN issues to improve security, reliability and performance........................................29
The file must always reside in the c: \ windows , and on all network computers......................................29
A.C 4.3 critically evaluate the performance of a LAN............................................................................31
References.................................................................................................................................................32
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Task 1
A.C 1.1 critically evaluate different LAN technologies
A network is a set of interrelated elements that are regulated in such a way that they can communicate.
It is fashionable to emphasize here the computer adage that says the network is the computer, that is to
say, that without the network the computer is under-exploited. Here are some examples of networking.
 The establishment of a computer network facilitates and secures the storage of information.
 It allows the standardization of applications and the sharing of data between workstations
efficiently.
 Well-designed networking facilitates management and maintenance of applications and computer
equipment.
 Networking can significantly reduce infrastructure costs.
Through the network, hardware and software resources are shared among several users. For example,
instead of buying multiple printers for each service, a printer can be shared by all services. It is the same
for distributed applications.
The different types of networks
There are different kinds of networks, depending on the size, information rate, types of communication
protocols, etc.
The architecture of local networks
There are several types of networks that differentiate among themselves according to the distance
between the computer systems or depending on the technology that allows to implement them.
Local area networks (LAN)
These are networks of more or less modest size, complex, which allow the exchange of computer data
and the sharing of resources (data, hard disks, various peripherals, etc.). The geographical extent of local
networks does not exceed 10 km (eg for a building or campus). The flow, or speed of communication,
varies from a few Mbps to 100 Mbps. The number of stations typically exceeds 1,000. A variant of the
LAN is the backbone or network basic (backbone) which is the main route taken by the traffic (Cisco, nd).
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Virtual Local Area Networks (VLANs)
A VLAN is a logical group of units or users that can be grouped by function, service or application
regardless of the location of their physical segment. The configuration of a VLAN is done in the switch by
software. Virtual Local Area Networks are not standardized and require the use of proprietary software
sold by the provider of switches. This type of network is seen in more detail in the next section.
Wireless local area networks (wireless, LAN or WLAN)
These are networks without visible physical connections. These networks use the waves (radio, infrared,
etc.) as a communication medium. Computers mobiles or personal assistants (Palm Pilot, etc.) constitute
the sector IT is growing faster. Many owners of this type of computers also have a computer connected
to LANs or WANs, at home or at home. Office, to which they are connected at all times
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A.C 1.2 critically analyse traffic intensive services and their performance
The term local area network, formerly defined as a network of computers located in the same enclosure,
currently designates a set of connected machines in the same field of diffusion. Information sent by a
computer in a broadcast to its network is thus received by all the stations of this network. The broadcast
domains, separated by routers, depend on architectures physical connection hardware. In local
networks, switches pose a problem. Indeed, it is the fact that switch fails to provide good information
access filtering contained in the frame headers of the network, transport or application layers. This
prompted manufacturers to think about a solution that can ensure the speed of the data. That’s the
reason that made the best solution was to replace in this architecture the switch by a router. This is able
not only to apply advanced filtering but also to split the “dissemination domain” into subdomains.
Unfortunately, the use a router to interconnect subnets also presents some disadvantages. Here are a
few:
An increase in slow communication between subnetworks: where the switch was simply guiding the
frame, the router must handle the header of the package contained in the frame.
More complicated management of IP addresses, because of the division into several DHCP domains,
each with its own DHCP server. It is noted that some routers can provide the DHCP server function
themselves. DHCP is the acronym of Dynamic Host Configuration Protocol which is a service
implemented in a network to automatically provide IP addresses to a device that connects.
Reduced flexibility: a machine that moves between two subnets can not, in general, keep its IP network
address, IPX, etc.
Also, the connection of machines to a concentrator - and, therefore, subnetting - is usually done on a
criterion of physical proximity, which does not correspond always to the organizational divisions and
therefore to the needs of access filtering (Cisco, nd).
It was, therefore, necessary that a new technology be developed to overcome these shortcomings. This
is how virtual local networks or VLANs came into being. The VLAN brought solutions, sometimes partial,
to these rather complex problems. Indeed, thanks to VLAN, it is now possible to disconnect the logical
structure of groups of workers of the physical structure of the network. Initially, this type of network
was based on proprietary solutions, but the development of IEEE 802.1Q standards has allowed today to
guarantee a certain interoperability. The purpose of the 802.1Q standard requires VLANs to be
compatible with MAC protocols of all standards802 series LAN (Ethernet, Token Ring, FDDI, Fast
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Ethernet, Gigabit, etc.).A VLAN, therefore, uses next-generation switches of the same type that Ethernet
or heterogeneous technology and which are interconnected by a network broadband backbone ( Fast
Ethernet, Gigabit Ethernet, FDDI, ATM ). A very important aspect for VLANs is that they can be limited to
a single switch or connect remote machines, connected to different switches. Thus, the “domains
“broadcast” are the individual VLANs. Even if the connection of a machine to a switch is done on a
criterion of physical proximity, this does not prevent this machine to be part of the same VLAN as
machines connected to another switch.
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A.C 1.3 Discuss LAN concerns and make recommendations to sustain network security,
reliability and performance
It was discussed as to why the VLAN is used and this was recommended as an improvement over LAN.
But, VLANs have intrinsic problems as well. As far as operation is concerned, we can distinguish different
types of VLAN.
 Level 1 VLANs based on port numbers. In that case, the membership of a machine to a VLAN
depends on the number of the port through which it is connected to the switch. This technique is
not flexible, in the where, whenever a machine has to be moved, it is necessary to redefine its VLAN
membership. Moreover, in some configurations, it is difficult to ensure a strict separation between
VLANs: a machine can possibly receive frames that are not intended for the VLAN to which she
belongs to.
 Level 2 VLANs based on the IEEE 802 MAC address (or address”Physical”). In this case, the
membership of a machine to a VLAN depends on the MAC address (Ethernet, etc.) of the machine. A
very good level of security can be assured because the MAC address is intrinsic to the network card
of the machine, and therefore cannot be modified by a malicious user. Furthermore, if the machine
is moved, the filter tables can be updated from automatically, so the administration of the VLAN is
simplified. On the other hand, initially set VLANs from MAC addresses is extremely tedious because
the MAC addresses are not structured and must be entered one by one.
The VLAN Layer 2 based on the identity of the higher level protocol indicated in the IEEE 802.2 header.
This technique can be applied to the condition of heterogeneity at level 3 protocols. interesting in that it
allows for the restriction of “broadcast” to machines whose network protocols make frequent use
diffusion (IPX, Appletalk, etc.), thus reducing the negative impact of this one on the other machines in
the network (Cisco, nd).
• The VLAN level 3 based on level 3 address (IP, network number IPX, etc.). All Level 3 address or
part only, sub number network, can be used to define the membership of a machine to a VLAN. Even if
the machine is moved, it keeps its level 3 address and therefore its membership in a VLAN. Since the
level 3 address can be modified by a malicious user (to change VLANs), this technology may pose
security problems. In addition, the obligation for a switch to look at the address in the level 3 header
increases its latency. In general, the switches used do not perform any function of routing and use the
level 3 address only to determine the VLAN to which the machine belongs. The definition of a VLAN from
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the level 3 addresses is simplified thanks to the hierarchical logical structure of these addresses
(network number, subnet number, number of machines).
• Higher level VLANs, based on different information present in successive headers of level 3, 4, or
more. The need to search information in successive headers, sometimes of variable format, significantly
increases the response time of the switches. We thus see that the definition of VLANs makes it possible
to separate groups of machines from the point of view of physical access. In addition, access to
machines several VLANs (servers, administrative stations) also exist, although general source of
problems for type 1 VLANs
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