Ronald DonaldsonD03554630TM585Tahereh DaneshiDeVry University-OnlineOct. 25th – Dec 21st

December 12th, 2010

Introduction(100-User Wireless LAN-Design & Implementation Analysis)

In this document, I will endeavor to provide a written analysis concerning the

design and implementation of a wireless LAN (WLAN) for a firm comprised of one

hundred employees. In illustration of the WLAN design, I will make reference to several

sources regarding any related content that I’ve found to be pertinent and of practical

benefit to this document’s purposes, not least of which is “Top-Down Network Design”,

by Priscilla Oppenheimer, an instructional text detailing a method of network design

that’s based upon what can be readily found evident throughout the overall networking

community to be the most logical and efficient sequence of steps necessary in the

creation of a network. Having stated this, it is of value for the reader to know that the

aforementioned sequence of steps, as examined in Oppenheimer’s work, will correspond

closely to the order of WLAN design and management issues that are addressed in this

document, and can be followed up by way of documentation found under the same title

and author at the end of this article.

The major design and management issues found unique to a WLAN involve those

pertaining specifically to the transmission and reception of radio frequency (RF) waves.

For example, there is the strategic placement of access points (AP), which are devices

designed to send and receive radio signals between nodes. This, in turn leads to a

consideration of any possibility of physical materials that may be found that could hinder

radio signals between APs, which will here be replaced by a ‘worst case’ factoring.

Protocols and standards dealing with wireless technology are also unique, as they

correlate directly to WLAN characteristics. In support of wireless communications,

physical wiring is also necessary, as the WLAN must at some point connect to a WAN.

Obviously, there are more wireless topics than are practical to mention in these few

opening lines. The point is, encompassed here within the following pages, presented with

thorough detail and explanation, are all of the elements necessary in order for the

sufficient insight and understanding of designing, implementing, and managing a WLAN

of the specified parameters. Lastly, as with any good LAN design, efforts have been

made to acknowledge the critical need for sustaining scalability and expandability.

Problem Statement(Network Design & Management Concentrations)

After careful and prolonged consideration of the prescribed ‘Terminal Course Ob-

jectives (TCOs)’, which serve to illustrate the primary elements and principal divisions of

concentration most suitably related to network design, I’ve had trouble only in choosing

which TCOs not to include within the subject matter of central focus. This due largely to

the overlapping and complementary nature of networking topics in general. At length, the

scope of this analysis has been refined within the context of TCO-B, concerning the ideal

formulation and configuration of a network that facilitates optimal performance, and

TCO-F, regarding the elements of a strategy found sufficient for fostering a maximum

state of security within a WLAN. Bear in mind, issues addressed here will necessarily in-

volve topics specific to other TCOs. Consequently, the integrated nature of their contents

requires they are at least made mention of, if only in connection to those of central focus,

otherwise, they will be given no priority.

The intention here, is to present the most plausible method and means by which

the specified WLAN may be configured, so as to be conducent to both performance and

security, as it could be argued, an optimal state of these combined network attributes

might afford management’s efforts with the space necessary from which to iron out and

overcome any adjunctive issues that may inevitably arise.

Analysis(Network Design Methodology, Variability, & Attribution)

As mentioned in the introduction, the concept flow of this document will follow

the top-down approach to network design. More specifically, as a form of structured de-

sign, the top-down approach is described by Oppenheimer, P., as “focusing on the re-

quirements, applications, and a logical structure before the selection of physical devices

and products to implement the design.” Accordingly, having identified the network as

wireless has filled a portion of the requirements already. The idea is simple, you can’t

know what would be best to use until you know exactly what it is your using it for, and so

the rationale behind this paper’s organization follows suit. Unfortunately, the greater part

of this WLAN presents the difficult challenge of omitting value from the majority of vari-

ables that are present, but thankfully, there’s a simple and effective means of dealing with

this, which will be discussed at greater length below. With this in mind, the general se-

quence of presentation and concept flow isn’t disrupted, and the underlying structural

current of thought throughout this document will proceeded naturally, top-down.

Serving as a supplemental concept to clearly interpreting the content and method-

ology behind the WLAN’s design, the sequence of decisions made throughout the top-

down approach utilized here coincides also with a more generalized life-cycle-develop-

ment process, characterized by the following four steps: of I.) Analyze the requirements,

II.) Develop the logical design, III.) Develop the physical design, and IV.) Test, optimize,

and document the design. (Oppenheimer, P.). While adhering to these structural aids,

(Top-Down Network Design and Life-Cycle-Development-Process) let us move now

within view of the first variables entering into the realm of consideration, as they are

found relating to the piecing together of a wireless local area network.

۞ Analyzing the Requirements ۞

The top-down method of design begins with an analysis of the business and tech-

nical goals that are associated with the network. Here there is ample breathing room as,

the only specifications that have been mentioned are the size of the network, (100 em-

ployees) and the fact that it utilizes wireless technology as a pivotal means of data trans-

mission. A note before moving on; I’ll not be attempting to speculate about the nature of

the firm’s operations, which my client desires to implement the WLAN for. However, it

may be beneficial to use examples to illustrate certain technical ideas. Having said that, in

addition to the established attributes of size and wireless capability, further dimensional-

ity to the network is provided by the chosen TCOs upon which we will focus, i.e., perfor -

mance and security. With no recourse to the intended use of the network, performance

and security will be applied in the most literal sense.

For example, in the interest of performance, every provision is made to ensure

the best possible performance of the WLAN within the specified parameters. This will

present certain challenges in regards to the second priority, security, which will also be

given precedence over anything not explicitly pertaining to either itself or performance.

In other words, ease of use and budget will be of secondary importance, and will only be

accommodated insomuch as they relate to either performance or security. So too will fol-

low, in the order of priority, all other issues. Already, we have run into several resultant if

not discrete contrasts between the central and decisive variables identified. In response to

the first major phase of the top-down design model, researching the client has been cut

short by the fact that we don’t know a great deal about what the network will be used for,

nor do we have details concerning the organization in general.

What we do know however is that despite the unnamed specifics, it can be as-

sumed that the business is either a remote and relatively isolated branch of a larger orga-

nization, or a relatively small company being comprised of only one hundred employees.

Also, we know that wireless communications are essential, so in the absence of precise

details to characterize the nature of those communications, our network must offer the

most scalable and proficient solution to the entire range of potential wireless applications

and environmental contexts. In my calculations regarding which applications and services

will be running over the WLAN, I can do little more than assume in each instance, that

the equivalent of a ‘worst case scenario’ is true. Provisions must be made for a state of

exemplary performance to exist under even the most demanding of circumstances, but

also with recourse to multiple applications of similar demand.

The above, may induce contrasting and thus difficult criteria, which will in turn

end up forcing the pressing trade-off decisions of performance between applications.

Though the model of reference here is the ‘worst case scenario’, for determining the pri-

ority of decisions which force trade-offs in performance between applications, I will en-

deavor to lean in the direction of what is most typical or commonly demanded, but only

where necessary will the priority of any one characteristic be held above another, as in the

anticipated instance of security vs. performance. In this case I must succumb to assigning

the TCOs themselves with priority, and will do so according to the order in which I chose

them (performance before security). Out of necessity, where a single solution that allows

for both optimal performance and security on the WLAN cannot be implemented, I will

resort to the aforementioned order. In either case, the primary objective for design and

implementation here is to be prepared for anything, and to provide ideal performance and

security in the face of it. At last, in addition to providing a design sufficient for optimal

performance and security, due considerations of future requirements must be taken into

account, which includes those topics pertaining to continued optimization through an ini-

tial state of scalability.

۞ Developing the Logical Design ۞

The primary difficulty in designing a WLAN for an organization without having

reference to the details and dimensions of the physical location’s characteristics, is that

there is little that can be done by the way of a site survey. To counter this shortcoming, it

must be assumed that there will be significant, if not drastic interference experienced by

an intervening wireless signal.

To that extent that, by accounting ahead of time for such obstacles, the degree to

which the impact from an actual instance of interference would be felt can be kept at a

minimal. By preparing the WLAN, in each scenario, for the worst, most of the impact

from indefinable variables will be absorbed before occurring, and if the worst doesn’t oc-

cur, than all the better for the network. To reiterate, this is the general angle of attack for

all unforeseeable variable relationships and interactions.

The first variable that needs to be addressed is network layer addressing, and

along those lines, the WLAN will utilize an internal DHCP server (D-Link DWS-4026),

as specified by Cisco.com, to be a viable fit. In order that the highest state of organiza-

tional, not to mention network, efficiency is adopted, a high level implementation of

structured addressing management will be necessary to avoid duplicate or dead address-

ing space. Addressing will be assigned on the basis of both public and private classifica-

tions, as a state promoting the highest degree of scalability, though public addressing only

in designated and controlled instances, whereas Network Address Translation is imple-

mented with the private addresses. (Oppenheimer, P.).

After having settled matters pertaining to addressing and naming, switching and

routing protocols are to be defined, on the basis of what the network’s anticipated opera-

tions will be characterized by. Here, WLAN characteristics are kept intentionally open-

ended; to account not only for a lack of specified network parameters, but also for the

highest degree of scalability, while maintaining optimal performance and security.

Network Layer Addressing & Naming

Network Layer Switching & Routing

Among variables factored into consideration here are network traffic characteris-

tics, bandwidth, memory, CPU usage, adaptability capacity, and general functionalities as

relate to performance and security. To begin, the WLAN will utilize a mesh topology as,

in the case of a relatively small network, (about 100-users) costs won’t be an issue, while

mesh networking offers the most reliable and scalable configuration, thus providing high

resiliency, which in turn factors into performance.

Because link-state routing protocols dictate sending and receiving of entire net-

work routing topology maps in addition to the pertinent sections of a routing table, link-

state routing is highly conducent to mesh networking. All attributes of the WLAN thus

far foster a very open and integrated functionality with all nodes connected, communicat-

ing with every other node through link-state routing, OSPF (Webopedia). adoption being

amongst the best known routing solutions of this kind, the way is paved for very fast and

very reliable routing and addressing, as well as any other matters dealing with perfor-

mance on a physical basis. Because each node bears the same connection potential in ev-

ery aspect, very little impact will be felt in the event of an emergency. (Dynamic Routing

Protocols). Also, the cost of OSPF is of no consequence here.

Due to the small size of this WLAN, as mentioned in “Top-Down Network de-

sign” it will be of benefit here to keep the entirety of all users within the WLANs own

subnet. This is said to be conducent to both security and management fluency due to the

heightened ease with which traffic filtering may be accomplished. (Oppenheimer, P.).

Network Security Planning

Utilizing the IEEE 802.11 standard, the WLAN is provided with the capacity to

use authentication at access points. By this measure, the degree of unauthorized network

traffic is controlled, and the risks to outside threat are minimized. (Oppenheimer, P.).

WPA2 is also advisable, being the latest and strongest encryption algorithm, supporting

Multiple in Multiple out (MIMO) technology, which is a means for ensuring the potential

of significantly stronger signal capacity, than non-MIMO technologies.

Bearing the trusted seal in all things ‘network’, Cisco certainly stands out ahead

of the pack as a strong consideration. Other Viable Options include Intel and D-Link.

While it is difficult to get a definite price on any kind of service agreement without call-

ing in for a quote, Cisco has stood the test of time not only defending its name against

competitors, but in customer satisfaction as well.

Implementation Suggestions(Physical Design Components and Configuration)

To conclude this document, ending comments will pertain to the general physical

implementation of the WLAN. Using a wireless mesh configuration that caters to one

hundred employees, the Cisco Aironet 1250 Series, though capable of accommodating as

many as 800 MAC addresses, would be more practical if place one per twenty five em-

ployees. This way, not only is there ample room for expansion, but also the existing traf-

fic requirements, whatever they may be, will be sufficiently accommodated and well

within range of 100% signal strength throughout. (Cisco.com).

WAN Providers

Having already mentioned the Cisco DHCP server model, DWS-4026, integrated

with the link-state OSPF routing protocol, there should be adequate functionality accom-

modations even for the most demanding traffic loads, as the combination of elements

here suggests a perfect interoperability. Adding to this general architecture the security

outlay discussed earlier and the way is paved for an optimally functioning wireless LAN,

well within means to perform ideally under harsh and/or uncertain conditions. A self con-

tained WLAN subnet acts as the most efficient means of firewall implementation without

sacrificing any notable degree of performance whatsoever. There you have it. Impervious

performance, impenetrable security, unmatched interoperability and potential for expand-

ability.

References

Cisco.com. Wireless LAN Controller Configuration. Retrieved Dec 13th 2010 from,

http://www.cisco.com/en/US/docs/wireless/controller/4.1/configuration/guide/c41wlan.html#wp1108097

Cisco Aironet 1250 Series. Cisco.com. Retrieved Dec 13th 2010 from,

http://www.cisco.com/en/US/prod/collateral/wireless/ps5678/ps6973/ps8382/product_data_sheet0900aecd806b7c6d.html

Clarity-Counseling.com Listing of Service Providers. Retrieved on Dec. 12th 2010 from,

http://www.clarity-consulting.com/wireless_solution_providers.htm#WLAN

D-Link.com. Network Hardware. Retrieved Dec 12th 2010 from,

http://www.dlink.com/category/productcategories/?cid=17

Dynamic Routing Protocols. CS.Virginia.EDU. PDF-File. Retrieved Dec 13th 2010 from,

http://www.cs.virginia.edu/~cs458/slides/module11-ospf.pdf

Hughs, A. (2010). Wireless Security Protocols. Ehow.com. Retrieved Dec 12, 2010, from

http://www.ehow.com/list_6691649_wlan-security-protocols.html

Oppenheimer, P. (2004). Top-Down Network Design. Indianapolis, IN: Cisco Press.

Mitchell, B. “Wireless Standards” About.com. Retrieved Dec. 12th 2010 from,

http://compnetworking.about.com/cs/wireless80211/a/aa80211standard.htm

Webopedia. (2010). Wireless Mesh Networks. Retrieved Dec 12th, 2010 from,

http://www.webopedia.com/TERM/W/wireless_mesh_network_WMN.html

Webopedia. (2010). Open Shortest Path First. Retrieved Dec 12th, 2010 from,

http://www.webopedia.com/TERM/O/OSPF.html

http://www.webopedia.com/DidYouKnow/Computer_Science/2006/OSPF_Routin g.asp