The Data Networking Designs Computer Science Essay

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The following is a network design report for Optichrome Ltd., a company providing computer animated special effects for the film and television industries. The company currently, has a workforce of 43 people, including 2 divisional managers and the CEO.

The company is divided into 3 managerial divisions: Marketing, Sales and Administration (employing 10 people), Animation and Modeling (employing 20 people), Rendering and Production (employing 10 people).

The company intends to rent one complete floor of a three floor office where the design needs to be implemented. The floor map of the office is shown further ahead in the report.

Network Requirements

Two computers per employee in the Rendering and Production division where 1 computer would be dedicated to the task of rendering ray traced animated frame and has software that requires it to work in a networked cluster with all the other rendering computers. The peak data rate required between any two computers is estimated to be about 300Mbps.

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One computer per employee in the Animation and Modeling division with an assumption that 2 or 3 computers may need to be linked for a project with a peak data rate requirement of 50Mbps.

One computer per employee in the Administration, Sales and Marketing division where the maximum expected data rate is 10Mbps.

One computer each, for the CEO and the divisional managers, with a maximum data rate of 10Mbps.

The design supports the company to expand its workforce by up to 50% and the entire network would be built around the netID 194.45.67.0/24 with each division separated using IP subnets and vLANs.

Data Network Design

The Network design is based on the Ethernet Local Area Network (LAN) technology and would require the following internetworking equipments:

CAT5 and CAT5e / CAT6 cables

Two 24 port Layer 2 Switches

One 48 port Layer 2 Switch

One 24 port Layer 3 Switch

The justification for the usage of the above mentioned equipments is given below and is evaluated later in the report.

Cabling

The building is equipped with CAT3 based twisted pair cable network. These cables are generally used for telephony and provide data rates up to 10Mbps. However, the network requirements suggest that the data transfer rates ranges from 10Mbps to 300Mbps across various divisions.

To meet these requirements, the floor would need to be networked using Category 5 or Category 5e cables (same as CAT6 cables). The general comparison of the CAT5 and CAT6 over CAT3 cables is listed below:

Category

Type

Length

LAN Applications

Speed

Notes

Cat3

UTP

100m

10Base-T, 4Mbps

Up to 10Mbps

Now mainly for telephone cables

CAT5

UTP

100m

100Base-Tx,ATM,CDDI

Up to 100Mbps

Common for current LANs

CAT5e/CAT6

UTP

100m

1000Base-T

Up to 1Gbps

Common for current LANs

(Anon, 2010; Hill and Linge, 2010)

From the above comparison, the use of CAT5 and CAT5e/6 cables can be justified for the different departments on the floor.

For requirements of up to 100Mbps (i.e. Animation and Modeling division; Administration, Sales and Marketing division; CEO and the divisional managers) CAT5 cables would be laid out on the floor and for the Rendering and Production division, where the peak transfer rate is 300Mbps, CAT5e cables would be laid out.

Network Division

The entire network would be divided into subnets and each division would be allotted a different subnet. The design would employ IP subnets and vLANs to achieve this. Each division would be in a separate vLAN, thus enabling integrity within divisions.

Inter-division communication will take place through a Layer 3 Switch, which acts as a router, on which various access policies can be employed to ensure safe data transfer between divisions.

Thus, the network would be divided in the following manner:

Animation and Modeling division would be allocated vLAN 1 (comprising of 20 computers)

Rendering and Production division would be allocated vLAN 2 (comprising of 20 computers)

Administration, Sales and Marketing division would be allocated vLAN3 (comprising of 10 computers)

Divisional Managers would be allocated in vLAN 4 (comprising of 2 computers)

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CEO would be in independent subnet allocated in vLAN 5 (1 computer)

For vLAN 1, the 20 computers would be connected to a 24 port Layer 2 switch.

Of these each computer is operated independently and if needed some computers can be linked together for a project.

For vLAN 2, the 20 computers would be connected to a 48 port Layer 2 switch.

Of these, 10 computers which would be dedicated for the rendering tasks and needs to be in a network cluster, would be connected on even ports of the switch.

The remaining 10 computers would be participating in the rendering tasks only during the night. Thus, these computers would be connected on odd ports of the switch, which would be inactive during the day and switched on during the night.

The additional ports could be used in case the company decides to expand its workforce.

For vLAN 3, the 10 computers would be connected to a 24 port Layer 2 switch which would be in a cluster to enable file sharing between office applications.

vLAN 4 and vLAN 5, with 2 computers and 1 computer respectively, would be configured on the same switch on which the vLAN 3 is configured, to avoid wastage of ports on the switch.

This is also convenient, as the cabling requirements for vLAN 3, 4 and 5 are the same i.e. CAT5 cables.

(The unused ports on each of the switches may be utilized in the future when the company plans the expansion of its work force.)

A Layer 3 Switch, which acts as a router, to which the three L2 switches are connected, would be used to for inter-vLAN routing.

Thus, all the intra-vLAN communication would be handled by the Layer 2 Switches and any communication between vLANs would be routed by the Layer 3 Switch.

The company may choose to connect the intranet to the external networks / internet if required.

The Layer 3 Switch is used as it comparatively cheaper than a router.

Adequate firewalls and policies need to be employed on the L3 Switch, to ensure various inter-vLAN access restrictions and access rules between the vLANs and WAN/internet and also to ensure that internal network is secure from external attacks.

Network Design

The data transfer requirements for vLAN 2 i.e. Rendering and Production division, is a peak rate of 300Mbps. To enable this, CAT5e/6 cables are used to network these computers. Along with that, each computer and the switch (S2) must be equipped with 1Gbps NICs (Network Interface Cards) to interface with the high speed cables.

While for the other vLANs, 100Mbps NICs can be used to interface with the CAT5 cables (i.e. for S1 and S3). Each of these switches would be connected to a Layer 3 Switch (S4).

As per the above mentioned network division, the network design would look like a star topology network shown below:

Figure1: Topological Diagram of the designed network

The links from S2 are wired using the CAT5e/CAT6 cables. Whereas, the remaining cables in the network are CAT5 cables.

The design shows how the switches are connected with each other and which vLAN is configured on which switch.

Based on the above topological design, the physical layout of the floor can be shown as per the floor plan below:

Figure 2: Physical layout of the designed network

The switches S1, S2 and S3 would be located on the floor as shown in the plan. The location of the switches is chosen such that the cable length requirements (maximum cable length is 100 meters) meet the dimensions of the floor.

CAT5 cables would be wired in the CEO's office, the Admin department, the Sales and Marketing department, the Animation & Modeling department and the two divisional manager's offices from switch S3.

CAT5e/CAT6 cables would be wired in Rendering & Production department from S2.

The location of the switches in the center of the floor permits the design to meet the length requirements of the CAT5 and CAT5e/CAT6 cables.

IP Address Specifications

The network is designed around the netID 194.45.67.0/24. The network design would employ IP subnets to separate and distinguish between various divisions and departments in the company.

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194.45.67.0/24  This IP range would provide 255 useable addresses to be configured on the network, but all belonging to the same subnet, which does not allow segregation of different divisions. Thus, the technique of IP subnets and vLANs is employed to achieve this.

IP Allocation

As per the current requirements, it is clear that the maximum number of computers in any subnet would be twenty (for Animation and Modeling division & Rendering and Production division)

Thus, it would be appropriate to use a mask of 27 bits (/27), allowing in all 32 host address to be configured on the subnet.

 vLAN 1:

The 1st subnet would be from: 194.45.67.0 /27 to 194.45.67.31 /27

From the above range, the first and the last addresses are the network address and the broadcast address of the subnet.

194.45.67.0 /27  Network Address

194.45.67.31 /27  Broadcast address

These 2 addresses cannot be used as host addresses i.e. they cannot be configured on to the computers.

Thus, this leaves 30 useable addresses starting from 194.45.67.1 /27 to 194.45.67.30 /27.

One IP address from the above range needs to be allocated to the port connecting S4 (router) and S1. This address becomes the default gateway address for this subnet on S1.

Let 194.45.67.1 /27 be the default gateway address for the subnet and addresses from the range 194.45.67.2 /27 to 194.45.67.30 /27 to be configured on the 20 computers.

Once the hosts are connected, the Switch is configured such that, the ports on which the 20 computers and S4 is connected is configured as vLAN 1.

In case of workforce expansion in the future, this subnet would have 9 available IP addresses which can be used.

 vLAN 2:

Similarly, the 2nd subnet would be from: 194.45.67.32 /27 to 194.45.67.63 /27

194.45.67.32 /27  Network Address

194.45.67.63 /27  Broadcast address

Thus, this leaves 30 useable addresses starting from 194.45.67.33 /27 to 194.45.67.62 /27.

One IP address from the above range needs to be allocated to the port connecting S4 and S2. This address becomes the default gateway address for this subnet on S2.

Let 194.45.67.33 /27 be the default gateway address for the subnet and addresses from the range 194.45.67.34 /27 to 194.45.67.62 /27 to be configured on the 20 computers.

Once the hosts are connected, the Switch is configured such that, the ports on which the 20 computers and S4 is connected is configured as vLAN 2.

In case of workforce expansion, this subnet would have 9 available IP addresses which can be used.

Note: As per the design, vLAN 2 is allotted for the Rendering and Production division, where in 10 computers, which needs to be in a network would be connected on even numbered ports on the S2 and the remaining 10 computers would be connected on odd numbered ports on the S2. The odd numbered ports would be active only during the night becoming a part of the network.

 vLAN 3:

The next requirement is of a subnet to host 10 computers in the Administration, Marketing and Sales division. Using a mask of /27 would be unwise in such a scenario.

It would be appropriate to use a mask of 28 bits (/28), allowing in all 16 host address to be configured on the subnet.

The 3rd subnet would be from: 194.45.67.64 /28 to 194.45.67.79 /28

194.45.67.64 /28  Network Address

194.45.67.79 /28  Broadcast address

This leaves 14 valid host addresses which starting from 194.45.67.65 /28 to 194.45.67.78 /28.

One IP address from the above range needs to be allocated to the port connecting S4 and S3. This address becomes the default gateway address for this subnet on S3.

Let the default gateway address for the subnet be 194.45.67.65 /28 and addresses from the range 194.45.67.66 /28 to 194.45.67.78 /28 to be configured on the 10 computers.

Once the hosts are connected, the S3 is configured such that, the ports on which the 10 computers and S4 is connected is configured as vLAN 3.

 vLAN 4:

The next requirement is of a subnet to host 2 computers for the 2 divisional managers. It would be appropriate to use a mask of 29 bits (/29), allowing in all 8 host address to be configured on the subnet.

The 4th subnet would be from: 194.45.67.80 /29 to 194.45.67.87 /29

194.45.67.80 /29  Network Address

194.45.67.87 /29  Broadcast address

This leaves 6 usable addresses which can be used from 194.45.67.81 /29 to 194.45.67.86 /29.

One IP address from the above range needs to be allocated to the port connecting S4 and S3. This address becomes the default gateway address for this subnet on S3.

Let the default gateway address for the subnet be 194.45.67.81 /29 and addresses from the range 194.45.67.82 /29 to 194.45.67.86 /29 to be configured on the 2 computers.

Once the hosts are connected, the Switch 3 is configured such that, the ports on which the 2 computers and S4 is connected is configured as vLAN 4.

 vLAN 5:

The next requirement is of a subnet to host only 1 computer for the CEO. It would be appropriate to use a mask of 30 bits (/30), allowing in all 4 host address to be configured on the subnet.

The 5th subnet would be from: 194.45.67.88 /30 to 194.45.67.91 /30

194.45.67.88 /30  Network Address

194.45.67.91 /30  Broadcast address

This leaves 2 valid host addresses which can be used: 194.45.67.89 /30 or 194.45.67.90 /30.

Off these, one IP address becomes the default gateway address for this subnet on S3.

Let the default gateway address for the subnet be 194.45.67.89 /30 and 194.45.67.90 /30 to be configured on the computer.

Once the host is connected, the S3 is configured such that, the ports on which the host and the router is connected is configured as vLAN 5.

Allocation Summary

vLAN 1 (S1): Animation and Modeling division

Host Addresses: 194.45.67.2 /27 to 194.45.67.30 /27

Default Gateway: 194.45.67.1 /27

vLAN 2 (S2): Rendering and Production division

Host Addresses: 194.45.67.34 /27 to 194.45.67.62 /27

Default Gateway: 194.45.67.33 /27

vLAN 3 (S3): Administration, Sales and Marketing division

Host Addresses: 194.45.66.66 /28 to 194.45.67.78 /28

Default Gateway: 194.45.67.65 /28

vLAN 4 (S3): Divisional Managers

Host Addresses: 194.45.67.82 /29 to 194.45.67.86 /29

Default Gateway: 194.45.67.81 /29

vLAN 5 (S3): CEO

Host Address: 194.45.67.90 /30

Default Gateway: 194.45.67.89 /30

Hence there would be IP addresses from 194.45.67.92 /27 onwards at the company's disposal (apart from the unused IPs available in subnets of each division) to accommodate workforce expansion in the future, where each additional host can be included in the above designed vLANs to become a part of the respective department.

Critical Evaluation

The evaluation of above mentioned design yields the following strengths and drawbacks:

Strengths:

The design involves the division of the workforce into vLANs, which enables logical separation between them.

The use of CAT5 and CAT6 cables enables the data transfer rates of the users to go up to 100Mbps and 1Gbps respectively. Also, the useable lengths of these cables (up to 100 meters), meets the cabling requirement.

Currently there are 53 connections required and the company plans to grow by 50%, which means additional port requirement would be around 27 (approximately). That means the total port requirement would be around 80. The use of 24 and 48 port switches which would be easily accommodated by the current design.

Along with this, the design uses IP subnets which provided the company with enough IPs which would their expansion generously.

The design uses a L3 switch which is cheaper than a router, thus proving cost effective. However, if the company budget permits, then a router can be also used for internet.

The design separates the logical domains of the CEO and the managers from their respective departments by allotting different vLANs to them. Thus, the communication between the hierarchies can be controlled.

The design also permits the company to acquire an internet connection, if required, which could be terminated at the L3 Switch.

In the design, the L2 switches are connected to a centrally located L3 switch in a star topology, which avoids formation of data loops, and undesirable conditions like 'Broadcast Storms' in the network and provides central access control over the network. (Hill and Linge, 2010)

Considering the above mentioned strengths, the design also has some drawbacks, which needs to be considered.

Drawbacks:

The design categorizes the company into hierarchies, with the CEO, managers and the departments being logically separated.

However, such a design causes the communication between the managers and their respective departments to go through an additional hop (causing a delay), which may be unfavorable in some situations.

The network is based on a star topology design which may prove undesirable as the entire network depends on the status of the central router/L3 switch.

If router fails, the entire network would collapse. So care must be taken that a stable router/L3 switch is installed for the network.

The network could also be designed by using three Layer 3 switches on which the different vLANs could have been configured and interconnected with each other and there wouldn't have been the need of an additional switch in the network. However, this design could have formed data loops and multiple paths in the network. (Hill and Linge, 2010)

Thus considering the above factors, the designed network is stable and sufficient for the requirements specified by the company with the flexibility provided to expand workforce of the company.