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.

Router Interfaces | Components of Router Hardware and Memory

Router Interfaces | Components of Router Hardware and Memory 

This article is an introduction of Router Interfaces, its Components of Router Hardware and Memory. In first part of this article we will discus the main components of router. Like other network devices, routers have the following main parts:

1. Input / Output Devices
2. CPU : to execute the OS instructions (Cisco routers use IOS as the operating system).
3. Memory (RAM, ROM, NVRAM and Flash) : A router has access to volatile and non-volatile memory storage, the latter needs constant energy to conserve information.

Router Memory Table.

Memory	Volatile / Nonvolatile	Store
RAM (SDRAM)	Volatile	• IOS running  • Configuration file running  • IP routing and ARP tables  • Packet buffer
ROM	Non volatile	• Startup instructions  • Basic diagnostic software  • IOS limited
NVRAM	Non volatile	• Startup configuration file
Flash	Non volatile	• IOS (Internetworking Operating System)  • Other system files

Hardware components of Router:

Although there are different types and models of routers, they all have the same general hardware components.

1. Power supply
2. Fan
3. Protection for WAN (WIC) or high-speed WIC (HWIC) interface card
4. Dynamic synchronous RAM (SDRAM) that is used to keep the configuration running and routing tables.
5. Non-volatile RAM (NVRAM) and boot flash memory used to store the ROMMON boot code and NVRAM data.
6. CPU
7. The connection of the advanced integration module (AIM) that downloads functions that demand a lot from the processor, such as encryption from the main CPU.
8. Protection for WAN (WIC) or high-speed WIC (HWIC) interface card

A network professional must know and understand the function of the main internal components of a router, rather than the exact location of these within a specific router.

Router Interfaces or Ports:

Routers have different types of interfaces or ports to support connections. Different router model have the different router interfaces according to their type and need. Following are the main types of router interfaces :

Console ports : 

Console port is used to access the administration of the initial configuration and the command line interface (CLI). There are two ports available, the most frequently used port (common RJ-45 port) and a new type B USB connector (USB mini-B). However, the console can only be accessed for one port at a time.

USB interfaces : 

Ports with the USB 0 and USB 1 label to provide additional storage space, similar to flash memory.

Gigabit Ethernet : 

Interfaces with the GE0 / 0 and GE0 / 1 label. Generally, they are used to provide LAN access by connecting with switches and users, or to interconnect to another router.

Auxiliary (AUX): 

An RJ-45 port for remote administration access, similar to the console port. It is now considered an old port, as it was used to support dial up modems.

Slots for enhanced high-speed WAN interface cards (eHWIC) : 

with the eHWIC 0 and eHWIC 1 label to provide modularity and flexibility by allowing the router to support different types of interface modules, including serial, digital subscriber line (DSL) , switch port and wireless technology.

CompactFlash slots : 

with the CPC and CF1 label to provide a larger amount of storage space in expandable Hash memory with CompactFlash cards up to 4 GB per slot. By default, the CFO slot has a 256 MB CompactFlash card and is the default boot location.

The connections of a Cisco router can be grouped into two categories: In-band router interfaces and management ports.

• Management Ports : (purple) These include the console and auxiliary ports used to configure, manage and troubleshoot the router. Unlike the LAN and WAN network interfaces, the management ports are not used for sending user traffic packets.
• In-band router interfaces : (orange) These are the LAN (i.e. Gigabit Ethernet) and WAN (i.e., enhanced high-speed WAN interface cards) interfaces configured with the assignment of IP addresses to transport traffic of users. Ethernet interfaces are the most frequent LAN connections, while common WAN connections include serial and DSL interfaces.

IN-BAND ROUTER INTERFACES

• Serial WAN interfaces (left) : which are added to the eHWIC0 and have the labels Serial 0 (i.e., S0 / 0/0) and Serial 1 (ie, S0 / 0/1). Serial interfaces are used to connect routers to an external WAN network. Each serial WAN interface has its own IP address and subnet mask, which identify it as a member of a specific network.

• LAN Ethernet network interfaces (right) : with the GE 0/0 (ie G0 / 0) and GE 0/1 (ie G0 / 1) labels. Ethernet interfaces are used to connect to other devices with Ethernet enabled, including switches, routers, firewalls, etc. Each LAN network interface has its own IPv4 address and subnet mask, or an IPv6 address and prefix, which identify it as a member of a specific network.

Computer Network Infrastructure and Component

Computer Network Infrastructure and Component

In this article we describe Computer Network Infrastructure and Component that is Devices, Media and Services with some common examples.

The route that takes a message from the origin to its destination can be as simple as a single cable that connects one PC to another or, as complex as a network that literally covers the world. This network infrastructure provides the stable and reliable channel through which communications occur.

The network infrastructure contains three categories of network components:

1. Network Devices
2. Network Media
3. Services

The devices and the media are the physical or hardware elements of the network. Typically, the hardware is composed of visible components of the network platform, such as a laptop, a PC, a switch, a router, a wireless access point (Access Point) or the wiring used to connect those devices .

Network Devices

The network devices that people are most familiar with are called terminals . Some examples of network terminals are shown in the following figure:

A network device is the origin or destination of a message transmitted through the network. To distinguish one terminal from another, each terminal in the network is identified by an address . When a terminal initiates a communication, it uses the address of the destination terminal to specify where the message should be sent.

Some examples of terminals:

• Computers (workstations, laptops, file servers, web servers)
• Network printers
• VoIP phones.
• TelePresence Devices.
• Security cameras.
• Mobile portable devices (such as smartphones, tablet PCs, PDA and wireless debit and credit card readers, and barcode scanners)

INTERMEDIARY NETWORK DEVICES

These devices connect the individual terminals to the network and can connect several individual networks to form an internetwork . They provide connectivity and guarantee data flow throughout the network.

These devices use the address of the destination terminal, together with information on the network interconnections , to determine the route that messages must take through the network. In the figure, some examples of the most common intermediary devices are shown:

Functions of intermediary network devices:

• Regenerate and transmit the data signals.
• Keep information about the routes that exist through the network and 
• networking. (Routers)
• Direct the data in alternative paths when there is a link failure. (Routers)
• Report errors and communication failures.
• Sort and direct messages according to QoS priorities
• Allow or deny data flow according to security parameters. (Firewall)

NETWORK MEDIA

Communication through a network is transported by means. The medium provides the channel through which the message travels from the origin to the destination.


Modern networks mainly use three types of means to interconnect devices and provide the route by which data can be transmitted. As shown in the following figure, these means are as follows:

TYPES OF NETWORK MEDIA

• Metal wires inside cables : the data is encoded in electrical impulses.
• Glass or plastic fibers (fiber optic cable): the data is encoded as light pulses.
• Wireless transmission : data is encoded with wavelengths of the electromagnetic spectrum.

To know what network medium we should use, let's take into account the following criteria.

CRITERIA FOR CHOOSING A NETWORK MEDIUM

• The distance by which the media can carry a signal correctly
• The environment in which the media will be installed
• The amount of data and the speed at which it should be transmitted
• The cost of the medium and the installation

NETWORK SERVICES

Finally, the services include a large number of common network applications that people use daily, such as email hosting services and web hosting services. The processes provide the functionality that directs and moves messages across the network. The processes are less obvious to us, but they are critical to the operation of the networks.

THE NETWORK AS A PLATFORM

If we look at separate traditional networks, we could realize that each network has its own rules and standards. These separate networks could not communicate with each other and each network would use different technologies to transport the communication signal.

Advances in technology allow us to consolidate these different types of networks on a platform known as "convergent network", which is the ability to transmit data, voice and video over the same
network infrastructure . A single network channel capable of sending these forms of communication.

THE NETWORK ARCHITECTURE

Networks must support a wide variety of applications and services, as well as operate through the different types of cables and devices that make up the physical infrastructure. The architecture of the network refers to the technologies that support the infrastructure and the services and the rules, or protocols, programmed that transfer the data through the network.

As networks evolve, we discover that there are four basic features that the underlying architectures need to meet user expectations:

• Fault tolerance : These networks depend on several routes between the origin and destination of the message. If a route fails, messages can be sent immediately by another link. The fact that there are several routes that lead to a destination is called "redundancy."
• Quality of service (QoS) : QoS becomes a primary mechanism to manage congestion and ensure reliable content delivery to all users. Congestion occurs when the demand for bandwidth exceeds the amount available. The bandwidth of the network is the measure of the amount of bits that can be transmitted in one second (bps).
• Security : The security of the infrastructure of a network includes the physical assurance of the devices that provide connectivity and prevent unauthorized access to the administrative software that resides in them.