How to Design a Small Office Network

How to Design a Small Office Network

This blog post is quick tutorial on "How to Design a Small Office Network". To meet user requirements, even small networks require planning and design. Planning ensures that all requirements, cost factors and implementation options are duly considered. Reliability, scalability and availability are important parts of a network design. To support and expand a small network, you need to be familiar with the protocols and network applications running on it. Common network protocols include DNS, Telnet, SMTP, POP, DHCP, HTTP and FTP.
Up to this point in the previous articles of CCNA, we have considered the services that a data network can provide to the human network, we have examined the characteristics of each layer of the OSI model and the operations of the TCP / IP protocols and we observe in detail Ethernet , a universal LAN technology. The next step is to learn how to gather these elements to form a network that works and can be maintained.

1. Typologies of Small Networks

Most companies are small businesses. Therefore, it is expected that most networks are small networks. In small networks, the network design is usually simple. The number and type of devices in the network are considerably reduced compared to a larger network. In general, network topologies for small networks consist of a single router and one or more switches . Small networks can also have wireless access points (possibly built into the router) and IP phones. As for the Internet connection, they usually have a single WAN connection provided by a DSL, cable or Ethernet connection.

The administration of a small network requires many of the same skills needed to manage larger networks. Most of the work focuses on the maintenance and troubleshooting of existing equipment, as well as the protection of network devices and information.

2. SELECTION OF DEVICES FOR SMALL NETWORKS

To meet user requirements, even small networks require planning and design. Planning ensures that all requirements, cost factors and implementation options are duly considered. One of the first design considerations when implementing a small network is the type of intermediary devices that will be used to support the network. For this, several factors must be taken into account:

• Cost : Cost is one of the most important factors when selecting equipment for a small business network. The cost of a switch or router is determined based on its capabilities and characteristics. The capacity of the device includes the number and types of ports available, in addition to the backplane speed. The cost of cable routing necessary to connect each device on the network must also be taken into account.
• Speed ​​and types of ports and interfaces : Choosing the amount and type of ports on a router or switch is a fundamental decision.
• Expandability : Network devices include modular and fixed physical configurations. Fixed configurations have a specific type and amount of ports or interfaces. Modular devices have expansion slots that provide the flexibility to add new modules as requirements increase. Care must be taken to select the appropriate interfaces and modules for specific media, as routers can be used to connect different numbers and types of networks.

Features and services of Operating System

Depending on the version of the operating system, network devices may support certain services and features, for example:

• Security
• QoS
• VoIP
• Layer 3 switching
• NAT
• DHCP

Routers can be expensive depending on the interfaces and features required. Additional modules, such as fiber optics, increase the cost of network devices.

3. IP ADDRESSING FOR SMALL NETWORKS

When implementing a small network, it is necessary to plan the IP addressing space . All hosts within an internetwork must have a unique address.
The following are examples of different types of devices that affect IP design:

• End devices for users
• Servers and peripherals
• Hosts accessed from the Internet
• Intermediary devices
• The planning and registration of the IP addressing scheme help the administrator keep track of the types of devices. For example, if a host address between ranges 50 and 100 is assigned to all servers, it is easy to identify server traffic by IP address.

Note. If the addresses for these resources are not planned and documented, it is not possible to easily control the security and accessibility of the devices. Each of these different types of devices should be assigned to a logical block of addresses within the network's address range.

REDUNDANCY IN SMALL NETWORKS

Another important part of network design is reliability . Even small businesses often rely heavily on the network for their operation. A network failure can have very expensive consequences. To maintain a high degree of reliability, redundancy in network design is required . Redundancy helps eliminate single points of error. There are many ways to obtain redundancy in a network. Redundancy can be obtained by installing duplicate equipment, but it can also be obtained by providing duplicate network links in key areas, as shown in the illustration.

Typically, small networks provide a single point of exit to the Internet through one or more default gateways. With a router in the topology, the only redundancy in terms of Layer 3 routes is obtained using more than one internal Ethernet interface on the router. However, if the router fails, the entire network loses Internet connectivity. For this reason, it may be advisable for small businesses to hire an account with a lower cost option from a second service provider as a backup.

4. Design Considerations for Small Network

Users expect immediate access to their emails and the files they are sharing or updating. To contribute to the assurance of this availability, the network designer must perform the following steps:

1. Step 1 . Provide security to file and mail servers in a centralized location.
2. Step 2 . Protect the location against unauthorized access by implementing logical and physical security measures.
3. Step 3 . Create redundancy in the server farm to ensure that files are not lost if a device fails.
4. Step 4 . Configure redundant paths to servers.

In addition, in modern networks, some form of video or voice over IP is often used to communicate with customers and business partners. This type of converged network is implemented as an integrated solution or as an additional form of raw data overlaid on the IP network. The network administrator must take into account the various types of traffic and their treatment in the design of the network. Routers and switches in a small network must be configured to support real-time traffic, such as voice and video, independently of other data traffic.
Traffic classes can be as specific as the following:

• File Transfer
• Email
• Voice
• Video
• Messenger service
• Transactional

In short, the goal of a good network design, even for a small network, is to increase employee productivity and reduce network downtime.

5. Common applications for small Network

The utility of networks depends on the applications that are in them. Within the application layer there are two forms of software processes or programs that provide access to the network: the network applications and the services of the application layer.

NETWORK APPLICATIONS

Applications are the software programs that are used to communicate through the network. Some end user applications recognize the network, which means that they implement the application layer protocols and can communicate directly with the lower layers of the protocol stack.

• Email clients and Web browsers are examples of these types of applications.

APPLICATION LAYER SERVICES

Other programs may require the assistance of application layer services to use network resources, such as file transfer or managing print queues on the network. Different types of data, whether text, graphics or video, require different network services to ensure that they are properly prepared for processing by the functions found in the lower layers of the OSI model. Each network service or application uses protocols that define the standards and data formats that should be used. Without protocols, the data network would not have a common way to format and address the data. It is necessary to familiarize yourself with the underlying protocols that govern the operation of the different network services to understand their function.

7. COMMON PROTOCOLS OF A SMALL NETWORK

Most of the work of a technician, whether in a small network or a large network, is related in some way to the network protocols. Network protocols support the services and applications used by employees in a small network. Common network protocols include the following:

• DNS : Service that provides the IP address of a Web site or a domain name so that a host can connect to it.
• Telnet : A service that allows administrators to connect to a host from a remote location and control the host as if they were logged in locally.
• IMAP, SMTP, POP (email): Uses the simple mail transfer protocol (SMTP), the post office protocol (POP3) or Internet message access protocol (IMAP).
• DHCP : Service that assigns the IP address, subnet mask, default gateway and other information to clients.
• HTTP : Used to transfer information between Web clients and Web servers.
• FTP : Service that allows the download and upload of files between a client and a server.

These network protocols make up the fundamental toolset of network professionals. Each of these network protocols defines the following:

• Processes at any end of a communication session.
• Types of messages
• Message syntax.
• Meaning of the information fields.
• How messages are sent and the expected response.
• Interaction with the next lower layer.

Many companies established a policy of using secure versions of these protocols, whenever possible. These protocols are HTTPS, SFTP and SSH.

8. REAL-TIME APPLICATIONS FOR SMALL NETWORKS

In addition to the common network protocols described above, modern companies, including small ones, often use real-time applications to communicate with customers and partners. While it is possible that a small company cannot justify the cost of a Cisco Telepresence solution for businesses, there are other real-time applications that are accessible and justifiable for small businesses. The network administrator must ensure that the appropriate equipment is installed on the network and that the network devices are configured to ensure delivery according to priorities.

• Infrastructure:  To support proposed and existing real-time applications, the infrastructure must adapt to the characteristics of each type of traffic. It must be determined whether existing switches and wiring can support the traffic that will be added to the network.
• VoIP : VoIP uses routers with voice capabilities. These routers convert the analog voice of traditional telephone signals into IP packets. After that, the router sends these packets between the corresponding locations. VoIP is much cheaper than an integrated IP telephony solution.
• IP Telephony : In IP telephony, the IP telephone itself performs voice to IP conversion. In networks with integrated IP telephony solution, routers with voice capabilities are not required. IP phones use a dedicated server for call control and signaling.
• Real-time applications : To transport streaming media effectively, the network must be able to support applications that require time-dependent delivery. The Real-Time Transport Protocol (RTP) and the Real-Time Transport Control Protocol (RTCP) support this requirement.

9. SCALING OF SMALL NETWORKS

Growth is a natural process for many small businesses, and their networks must grow accordingly. Ideally, the network administrator has sufficient time to make intelligent decisions about the growth of the network in relation to the growth of the company.
To scale a network, several elements are required:

• Network documentation : physical and logical topology.
• Device inventory : list of devices that use or make up the network.
• Budget : detailed IT budget, including equipment acquisition budget for the fiscal year.
• Traffic analysis : protocols, applications, services and their respective traffic requirements must be registered.

These elements are used to support the decision making that accompanies the scaling of a small network.

10. EVOLUTION OF THE PROTOCOL REQUIREMENTS

Network administrators should be aware of how network use changes. As shown in the illustration, small network administrators have the ability to obtain “snapshots” of IT in person from the use of applications by employees for a considerable portion of the workforce over time.
Generally, these snapshots include the following information:

• OS and OS version
• Non-Network Applications
• Network applications
• CPU usage
• Unit utilization
• RAM utilization

The registration of snapshots of employees in a small network during a given period is very useful for informing the network administrator about the evolution of protocol requirements and related traffic flows.

For example, some employees may use external resources, such as social media, to better position a company in terms of marketing. When these employees started working for the company, they may not have given so much importance to Internet-based advertising. This change in resource utilization may require the network administrator to change the allocation of network resources accordingly.