Network Classification by Specialised Functions

Welcome everyone!
If you have been following my recent blog posts, you'd know that we have studied networks of various kinds by classifying them on the basis of:

1. The respective ranges those networks have and the areas they cover. These include PAN, LAN, WLAN, MAN and WAN.
2. The functional relationships those networks share. These include Client-Server Networks and Peer-to-Peer (P2P) Networks.
3. The way the nodes of the network are arranged to form the network. In other words, on the basis of the network topology. These include Bus, Star, Ring, Mesh and Tree Networks.

After we have studied all these types of network, we can be confident of possessing a basic fundamental idea of the organization of the networks around us. However, some types of networks have come up with advancements in technology which are so diverse in features and so important in today's world, that it is almost imperative that we must study about them. They perform a variety of roles in a variety of fields serving a variety of people with a variety of interests. We can hence classify networks based on specialised functions. While studying these networks, a basic thing to be kept in mind is that these are very complex and differentiated networks, possibly utilizing a number of technologies which are complex as well. These are a lot different than the basic networks we have studied till now. We'll be covering a particular number of them in this post.
Hence lets get started!

Network Classification by Specialised Functions

1. Storage Area Network (SAN)
2. Value Added Network (VAN)
3. SO/HO Network
4. Virtual Private Network (VPN)

Storage Area Networks

A storage area network (SAN) is a dedicated network that provides access to consolidated, block level data storage. SANs are primarily used to enhance storage devices, such as disk arrays, tape libraries, and optical jukeboxes, accessible to servers so that the devices appear like locally attached devices to the operating system. A SAN typically has its own network of storage devices that are generally not accessible through the local area network (LAN) by other devices. SAN implementation simplifies information life cycle management and plays a critical role in delivering a consistent and secure data transfer infrastructure.  

There are two types of SAN Solutions available:

1. Fibre Channel (FC): Storage and servers are connected via a high-speed network of interconnected fiber channel switches. This is used for mission-critical applications where uninterrupted data access is required. SANs using this technology are called FC SANs.
2. Internet Small Computer System Interface (iSCSI) Protocol: This infrastructure gives the flexibility of a low-cost IP network.

The choice of using one of them is based solely over business requirements.
Let us now look upon the reasons I included this network in my study. In other words, lets look upon the advantages of a SAN.

1. Storage Virtualization: Server capacity is no longer linked to single storage devices, as large and consolidated storage pools are now available for software applications.
2. High-Speed Disk Technologies: An example is FC, which offers data retrieval speeds that exceed 5 Gbps. Storage-to-storage data transfer is also available via direct data transmission from the source to the target device with minimal or no server intervention.
3. Centralized Backup: Servers view stored data on local disks, rather than multiple disk and server connections. Advanced backup features, such as block level and incremental backups, streamline IT system administrator responsibilities.
4. Dynamic Failover Protection: Provides continuous network operation, even if a server fails or goes offline for maintenance, which enables built-in redundancy and automatic traffic rerouting

Here is a diagrammatic representation of a SAN.

Part by Part of a Storage Area Network (SAN); Image Courtesy: netiisproperties.com

With this, I'd switch over to our next network.

Value Added Network (VAN)

A value-added network (VAN) is a private network provider (sometimes called a turnkey communications line) that is hired by a company to facilitate electronic data interchange (EDI) or provide other network services. Before the arrival of the World Wide Web, some companies hired value-added networks to move data from their company to other companies. With the arrival of the World Wide Web, many companies found it more cost-efficient to move their data over the Internet instead of paying the minimum monthly fees and per-character charges found in typical VAN contracts. In response, contemporary value- added network providers now focus on offering EDI translation, encryption, secure e-mail, management reporting, and other extra services for their customers.

The following example would help you understand better.

An example of a Value Added Network; Image Courtesy: sage.co.uk

SO/HO Network 

SO/HO stands for Small Office/ Home Office. It’s usually used to describe an office with ten to fifteen people or less on the network. The small office can be a wired network, a wireless network, or a combination of both. However, just because an office has less than ten or fifteen people on the office network, doesn’t mean that computer and networking professionals will consider it a small office network. This is because of the fact that the term is also used to describe the type and complexity of the equipment running the office network. If the network has all the office computers connected to a router, it’s considered a small office network. However, once something more advanced, such as a bridge or switch, is used to connect the computers to the network it stops being considered a small office network. When the term SOHO is applied to a home office, the same requirements as above are normally taken into account. Yes, this means that a home network can sometimes not be considered a SOHO network. If there are more than fifteen or so computers on the network, most computer and network professionals wouldn’t consider it a small network, and thus technically not a SOHO network. This means that if your home or office network uses something like a Belkin or D-Link router to connect the computers to the network, or if it uses a simple hub, it’s considered a SOHO network, no matter what type of Internet connection is used, if any.

Image Courtesy: flylib.com

Virtual Private Network (VPN)

A virtual private network (VPN) is a network that uses a public telecommunication infrastructure, such as the Internet, to provide remote offices or individual users with secure access to their organization's network. A virtual private network can be contrasted with an expensive system of owned or leased lines that can only be used by one organization. The goal of a VPN is to provide the organization with the same capabilities, but at a much lower cost. A VPN works by using the shared public infrastructure while maintaining privacy through security procedures and tunneling protocols such as the Layer Two Tunneling Protocol (L2TP). In effect, the protocols, by encrypting data at the sending end and decrypting it at the receiving end, send the data through a "tunnel" that cannot be "entered" by data that is not properly encrypted. An additional level of security involves encrypting not only the data, but also the originating and receiving network addresses.

Let us now have a view on the Protocols used for implementing a VPN.

VPN Protocols

The number of protocols and available security features continue to grow with time. The most common protocols are:

1. PPTP – PPTP: has been around since the days of Windows 95. The main selling point of PPTP is that it can be simply setup on every major OS. In short, PPTP tunnels a point-to- point connection over the GRE protocol. Unfortunately, the security of the PPTP protocol has been called into question in recent years. It is still strong, but not the most secure.
2. L2TP/IPsec: L2TP over IPsec is more secure than PPTP and offers more features. L2TP/ IPsec is a way of implementing two protocols together in order to gain the best features of each. In this case, the L2TP protocol is used to create a tunnel and IPsec provides a secure channel. This makes for an impressively secure package.
3. OpenVPN: OpenVPN is an SSL-based VPN that continues to gain popularity. The software used is open source and freely available. SSL is a mature encryption protocol, and OpenVPN can run on a single UDP or TCP port, making it extremely flexible.

Let us now have a look finally, at what makes us include Virtual Private Networks in our study of networks.

Advantages of a VPN

1. Encapsulation: VPN technology provides a way of encapsulating private data with a header that allows the data to traverse the network.
2. Authentication: There are three types of authentication for VPN connections:
1. User Authentication: For the VPN connection to be established, the VPN server authenticates the VPN client attempting the connection and verifies that the VPN client has the appropriate permissions. If mutual authentication is being used, the VPN client also authenticates the VPN server, providing protection against masquerading VPN servers.
2. Computer Authentication with IPsec/ L2TP: By performing computer-level authentication with IPSec, L2TP/IPSec connections also verify that the remote access client computer is trusted.
3. Data Authentication and Integrity: To verify that the data being sent on an L2TP/IPSec VPN connection originated at the other end of the connection and was not modified in transit, L2TP/IPSec packets include a cryptographic checksum based on an encryption key known only to the sender and the receiver.
3. Data Encryption: Data can be encrypted for protection between the endpoints of the VPN connection. Data encryption should always be used for VPN connections where private data is sent across a public network such as the Internet. Data that is not encrypted is vulnerable to unauthorized interception. For VPN connections, Routing and Remote Access uses Point-to-Point Encryption (PPE) with PPTP and IPSec encryption with L2TP.
4. Address and Server name: When a VPN Client is connected with the VPN Server, a point-to-point VPN connection is made along with the assignment of IP addresses and Domain Name Systems (DNS).

Keeping the above VPN properties it can be said that a VPN not only offers you anonymity as using a Proxy Server does, but also offers you the advanced encryption of the data by “tunneling” it over through the Internet, where the Internet serves as the very Backbone of this network, which removes the need of using Leased line connections to set up WAN.

Image Courtesy: gta.com

And with this I'd like to conclude my Classification of Computer Networks study. I'd advise you to read our general article over Computer Network Classification to have an overview of the topic. I really hope you enjoyed it and in the end got a great wealth of knowledge that will serve you greatly in future!