Subnetting And VLSM For Efficient Network Address Allocation

The Need for Subnetting

Question:

Discuss about the CCNA Exploration Companion Guide.

The system needs us to subnet the network into individual networks which are unequal. The IT department requires a sizeable subnet to accommodate 520 workstations and allow room for expansion as the sales department requires a smaller subnet to handle the 40 workstations. Dividing the network into subnets will give classes of Subnet masks which will best suit each unit with considerations of the hosts each department will need and the available hosts in each subnet mask.

The workstations will be interconnected by the Access points for all the devices that can access wireless internet and there will be the main switch from the primary router from where all the other switches will be connected (Abbate, 2010). All the other workstations will be linked via Ethernet cables because they are more reliable than the wireless network and less prone to errors and hitches. From the main distribution, switch will be connected all the other switches that lead to different offices of the department so that every office will have its switch and if need be, an Access point.

For more efficiency in the implementation of the addressing space, using Variable Length Subnet Masking (VLSM) is recommended to allow the use of different masks for every subnet (Moran, 2010). The Variable Length Subnet Masking will assist in the creation of subnets large enough and with more than 255 addresses for the host. Use of the Variable Length Subnet Masking will enable us to assign IP addresses with a minimal number of Internet Protocol addresses wastage thereby leaving a surplus.

All units will consist of a setup like the one shown below.  The primary router will interconnect each unit to the head office. The router will connect to the main switch which will be connected to other switches that will connect to the end devices (Comer, 2011). The access point will be linked to the primary router, and some devices will connect to the network via the access point. The switch shown is the main distribution switch which connects directly to the router. All other switches will connect to the main switch unless the office spans a very large area where there will need to connect the switches to a bridge.

The router will be connected to the modem which will allow it to access the internet and connect to the other routers from the other offices (James F. Kurose, 2008). All the routers will be linked to the web via the virtual private network so that their IP addresses will not be visible to other devices on the internet but not in the company's private network.

Allocating IP Addresses with VLSM

Every department will have an Access Point which will make it easier connecting devices which may not need an ethernet cable for connection. Switches interconnection and configuration as per the subnets is shown below (Institute). 

The subnet masks will be calculated as below. The 10.0.0.0 IP address is a class A network. With the use of VLSM to allocate Internet Protocols in every department gives us the below subnets:

The IT department is the largest department and therefore needs the biggest range of IP address (Mogul & J., August 2009). We shall, therefore, assign a high range of IP addresses as per the high usage requirements. It will, therefore, adopt subnet mask 255.255.252.0 and 10.0.0.0/22. The start IP address will be 10.0.0.1 and end IP 10.0.3.254. As per the departmental demands, the subnet mask used will be the best regarding wastage of IP addresses and allow room for expansion (Press C. ). All the devices and workstations in the IT departments will, therefore, use IP addresses between the given start host IP address and end host IP address. 

The Office of Finance is 2^nd in the IP address needs. With the use of the subnet mask 255.255.254.0, the Internet Protocol address will be 10.0.0.0/23. The finance department will be suited by the sub network since its hosts are below 508. It will be the best having the minimum possible wastage of IP addresses and the start IP host address will be 10.0.0.1 and end with 10.0.1.254.

The Office of Transport and logistics is third in IP requirements and will consist of a subnet mask of 255.255.255.0 and an IP address with 10.0.0.0/24. The beginning IP address will be 10.0.0.1 and end in 10.0.0.254. This will suit the department’s need providing all the required IP addresses and leaving a surplus which will cater for any increase in the number of hosts instead of restructuring the whole network.

The research office is holding approximate 120 workstations will fall under the 255.255.255.128 subnet mask. It will take a 25-subnet mask IP address of 10.0.0.0/25. Beginning IP address will be 10.0.0.1 and end IP will be 10.0.0.126. It will allow 125 host workstations which are the best fit for our research office department. Being more than the department needs will cater for any other hosts that may require IP addresses in future and also is the best regarding wastage of IP addresses.

The head office has 60 workstations. It will, therefore, have a subnet mask of 255.255.255.192 with an IP address with 26 subnet mask bits of 10.0.0.0/26. Beginning IP address will be 10.0.0.1 and end with 10.0.0.62. It will, therefore, be the best fit for our head office having sixty-one host IP addresses available.

Monitoring and Securing a Network with Network Analyzers

The sales office has an approximate of 40 workstations. It will adopt a subnet mask of 255.255.255.192. It will have an IP address with 26 subnet masks of 10.0.0.0/26. Beginning IP address will be 10.0.0.1 and end IP will be 10.0.0.62.

The addressing solution leaves enough space for expansion within the departments and makes sure of minimal IP address wastage (Institute). With the research office having ten workstations, it is at a needful point with a subnet of 126 hosts. Further expansion of the department will require reviewing the entire addressing scheme.

The Head Office having 60 workstations will need a 62-host subnet. Loss of IP address is minimized by having two free addresses in the subnet. In case the office expands with an extra two workstations, the entire addressing scheme should be reviewed.

Using the VLSM addressing procedure fits well for the subnets since some are as large as 255 hosts like the IT department subnet. It should, therefore, be addressed a manner that will allow future expansion (Cerf, Vinton G., Kahn Robert E., 2013). It is also necessary to have small subnets to avoid loss of addresses. Using the method ensures there is minimal wastage by giving IP addresses close to the needed and avoiding loss of IP addresses by having a sub network with many host IP addresses but only a few hosts to connect to it. It also caters for growth by leaving a surplus IP addresses and therefore, if there is need to upgrade the network by increase the number of hosts, it will not be necessary to restructure the whole system design.

A TCP/IP network will always require close monitoring to make sure it is up and running to check any devices that may be experiencing a breakdown. It will help ensure the network is running correctly and serving all its needs. It is also important to keep monitoring the security of the network to make sure that there are no intruders who penetrate the system and to ensure that all unauthorized persons do not gain access to a workstation or a device they are not supposed to (Press C. , 2010).

Network administrators are supposed to give reports on a timely basis about the network. However, it is hard for a network admin to keep analyzing the operations of the system and detect any problems that arise. That is the reason they need Network Analyzers.

The Network analyzers, therefore, are used by the network administrators to help analyze and diagnose problems occurring in the network and the network analyst will have easy time predicting the source of the problem and the best troubleshooting techniques they can employ.

This is important in keeping a monitor all day and night and better than having the network administrator keep an eye all time. It would be easy for an intruder to get in and tamper with the system without the administrator getting a clue unless the system fails.

It is usually easier for the network administrator to troubleshoot and diagnose the system when there is a failure at any node when they are using a network analyzer (Postel, January 2014). The network analyzer will provide all the requirements needed to monitor and manage the network system. The network analyzer will track the Wide Area Network and the Local Area Network status and statistics which will help in reviewing the security of endpoints. These will contribute to keeping a continuous and timely update of the network which is a basic need for a busy network that is to be kept up and running. It ensures that the reports the network administrators give are correct and timely since the analyzer system will keep logs of all time even when the administrator may not have seen.

All the data packets that have been transmitted or received on the network will be monitored by the analyzer, and it will be evident when some malicious content is allowed into the network system. The network analyzer can automatically block the intruder all notify the administrator to take the necessary action (C., 2016). The network analyzer will also help in verification of any change in the system to help know whether it is genuine by use of filters, firewalls, and proxies.

The network analyzer ensures that the system is kept secure. All the subnets will be connected via the internet, and therefore an intrusion may occur in any of the six offices. It is therefore important to have a central place of analysis.

There are many network analyzers made available by different software development companies. Most of them work similarly and differ in their method of interception of log traffic (Tanebaum, 2008). Wireshark is one of the network analyzer software running on most Unix and Windows platforms. Wireshark can be able to view Transmission Control Protocol sessions and record logs on the sessions. Most network analyzers work by consoles while Wireshark's console is inclusive. It is, therefore, better to use Wireshark than other network analyzers provide it is kept up to date.

As displayed by the Wireshark logs screenshot, it is possible to understand the working on it and its logs even when one is not a trained Network admin. The software is also open source which makes it easy to get timely updates.

References

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Cerf, Vinton G., Kahn Robert E. (2013). The introduction of packet satellite communication.

Comer, D. (2011). Internetworking with TCP/IP Principles, protocols, and architectures.

Dye, M., McDonald, R., & Rufi, A. (2012). Network Fundamentals, CCNA Exploration Companion guide. Cisco Press.

Institute, I. S. (n.d.). Internet Protocol. Internet Program Protocol Specification. Retrieved from www.tools.ietf.org/html/frc791#page-7

James F. Kurose, K. W. (2008). Computer Networking.

Mogul, J., & J., P. (August 2009). Internet Standard Subnetting Procedure.

Moran, J. (2010, September 1). Understanding and resolving IP Address conflict. Retrieved from www.webopedia.com

Postel, J. (January 2014). Model of Operation. In I. S. Institute, DOD Standard Internet (p. 5). Marina del Rey, California: University of California.

Press, C. (2010). Network Security Architectures. General Design Considerations for Secure Networks.

Press, C. (n.d.). IP addressing guide. Retrieved from www.cisco.com/web/about/ciscoitatwork/downloads/ciscoitatwork/pdf/Cisco_IT_IP_Addressing_Best_Practices.pdf

Tanebaum, A. S. (2008). Computer Networks.