Thursday, September 29, 2011

Network Equipment, Basic Knowledge You Need to Get

Computer networking devices are units that mediate data in a computer network. Computer networking devices are also called network equipment, Intermediate Systems (IS) or InterWorking Unit (IWU). Units which are the last receiver or generate data are called hosts or data terminal equipment.

The Internet has truly revolutionized the way we communicate. If you actually think about it, the Internet is computer networking at the highest scale of complexity. It’s a continuous link of connected computers that spreads worldwide. How is data transfer and the implementation of networking protocols made possible in this colossal network? It is made possible because of networking devices that regulate data traffic over the whole network, providing connectivity and control. The network design is based on the OSI (Open Systems Interconnection) model. Router, switch, hub and bridge are networking devices that act as mediators at various levels of this networking model.

What are the differences in the design and functioning of these networking devices: router, switch, hub and bridge?
Every one of these network devices which we compare in the following is a part of every Large Area Network (LAN), Wide Area Network (WAN) or small private networks. They integrate and connect the network at various levels, while providing control over data flow.

The main differences in functionality of Router, Switch, Hub and Bridge
A computer network connected to the Internet is designed to be a self-regulating network that can guarantee the transmission of data to right destinations and regulate overall data transfer. The network can be primarily divided into two types of devices which are terminals (connected computers) and control elements or connecting devices. The role router, switch, hub and bridge play in a computing network determines their basic functionality and difference.

Two or more computing networks are connected together by a router. It is charged with the responsibility of controlling the inter network data traffic. They are highly intelligent devices with embedded software that are used to control the flow of data packets across diverse networks.

A network switch is charged with the job of connecting smaller segments of a single network into a connected whole. They are extensively used in Ethernet local area networks.

A hub connects various Ethernet devices to integrate them into a whole network segment. It is one of the most basic hardware devices that connect two or more Ethernet terminals in a network.

A network bridge is nothing more than a type of switch. While a switch has multiple connection ports, a bridge has a single connection port. In the next section, let us have a look at the features of each one of these devices in more detail.

Referring to OSI model layers, a router is functional on the network layer of the OSI model, which is also known as level 3. They integrate logical subnet together and their operation is made possible by inbuilt operating systems. They are designed to calculate the best possible path for transmission of data packets between networks. The basis for routing of data through a router is the use of Internet protocol addresses. You might want to check out the OSI model diagram to understand the functions of these devices better.

Network switches are functional on the layer 2 of the OSI model. This layer is often referred to as the data link layer. Network switches transfer data across a network segment using MAC addresses for reference.

A hub operates only at layer 1 level of OSI model, which is the physical layer. Integrating Ethernet terminals together is its only function and it is a passive device used for data transfer. A bridge is just a type of network switch that connects two network segments together. Like switches, they too operate at the data link layer.

All these networking devices provide connectivity and help regulate Internet traffic through local and global Internet networks. Tips of identifying what are main networking hardware help you know the role and function of router, switch, hub and bridge in a network. So which network equipment you select depends on what you need in your home network or business network.

More Related:
Common basic networking devices:
Router: a specialized network device that determines the next network point to which it can forward a data packet towards the destination of the packet. Unlike a gateway, it cannot interface different protocols. Works on OSI layer 3.

Bridge: a device that connects multiple network segments along the data link layer. Works on OSI layer 2.

Network Switch: a device that allocates traffic from one network segment to certain lines (intended destination(s)) which connect the segment to another network segment. So unlike a hub a switch splits the network traffic and sends it to different destinations rather than to all systems on the network. Works on OSI layer 2.

Hub: connects multiple Ethernet segments together making them act as a single segment. When using a hub, every attached all the objects, compared to switches, which provide a dedicated connection between individual nodes. Works on OSI layer 1.
Repeater: device to amplify or regenerate digital signals received while sending them from one part of a network into another. Works on OSI layer 1.

Some hybrid network devices:
Multilayer Switch: a switch which, in addition to switching on OSI layer 2, provides functionality at higher protocol layers.
Protocol Converter: a hardware device that converts between two different types of transmissions, such as asynchronous and synchronous transmissions.
Bridge Router (B router): CombineS router and bridge functionality and are therefore working on OSI layers 2 and 3.

Hardware or software components that typically sit on the connection point of different networks, e.g. between an internal network and an external network:
Proxy: computer network service which allows clients to make indirect network connections to other network services
Firewall: a piece of hardware or software put on the network to prevent some communications forbidden by the network policy
Network Address Translator: network service provide as hardware or software that converts internal to external network addresses and vice versa

Other hardware for establishing networks or dial-up connections:
Multiplexer: device that combines several electrical signals into a single signal
NetworkCard: a piece of computer hardware to allow the attached computer to communicate by network
Modem: device that modulates an analog "carrier" signal (such as sound), to encode digital information, and that also demodulates such a carrier signal to decode the transmitted information, as a computer communicating with another computer over the telephone network
ISDN terminal adapter (TA): a specialized gateway for ISDN
Line Driver: a device to increase transmission distance by amplifying the signal. Base-band networks only.

Thursday, September 22, 2011

Best Cisco 800 Series Routers Help You Prepare for CCNA Exam & CISCO IOS

So many new or aspiring network administrators have asked me "what is the best router to use to learn the Cisco IOS?", or "what is the best router to use to practice for your CCNA exam?", or even, "what is the best router to use to connect your home or small business to the Internet?". While there are certainly less expensive options that might try to fulfill all three of these needs, in my mind at least, there is one clear answer. That is the Cisco 800 series routers. In this article, we will take a look at what this router line can do and how it can fulfill all of these needs.

What is the scoop on Cisco 800 series routers?
The Cisco 800 series router lineup is the least expensive and least performance router that Cisco puts their name on (in their current product line up, that is). While Cisco does own Linksys, I am not counting line system routers in this discussion, other than to say that they are lacking the Cisco IOS and all the features that the IOS brings.

I am certainly not selling Cisco routers so the point of this article is to only inform you about a product that just might fit your needs perfectly, as it did in my case. With that, let's learn more about this Cisco 800 series product line...

Here is what you need to know: 

The 800 series routers run the Cisco IOS and have most of the latest and greatest features.
The 800 series comes in at least 13 different models with varying versions of the IOS on each so take some time looking at the Cisco 800 series model comparison chart before you make up your mind which one to buy.

There are 800 series routers that connect to all different types of WAN connections - Ethernet (such as to a cable model), ISDN, Serial (such as to a T1 circuit), and G.HDSL/ADSL directly.

On the LAN side, the 800 series routers support 802.11 b/g wireless and your Ethernet LAN.

Yes, the 800 series routers have a GUI interface (called the SDM, discussed below) but, candidly, if all you are going to configure the router with is the GUI interface then don't waste your money - buy a Linksys instead. The real power of the 800 series router is the Cisco IOS CLI.

When it comes to security, Cisco 800 series routers support IPSEC VPN tunnels, VPN remote access, SSL VPN, Stateful firewall, and basic IPS (but make sure you get the right version of the IOS to go on your router - the IOS Advanced Security Image).

The street price for a Cisco 800 series routers ranges in price from about $250 to close to $1000. However, you can find these for less by shopping around on the Internet or even by buying one used on Ebay. As these are Cisco's lower end routers, there are a lot of companies that sell them and a lot of competition on pricing.

So, all in all, the Cisco 800 series router packs a powerful punch.


What is the best router to use to practice for your CCNA exam?

Frequently, I help candidates who are preparing for the Cisco CCNA exam and hope to move on to the CCNP exams at some point. They need to get at least one router to practice their IOS configurations - both for the hands-on portion of the CCNA exam and just to become competent navigating the Cisco IOS.

While you could buy a used 2500 or 2600 series router from Ebay for less (or much less, in the case of the 2500 series), I have been recommending the 800 series primarily because the 800 series can run the latest and greatest version of the IOS code. To run a version of the IOS that is even remotely current on a 2600, you will need to upgrade it to the maximum amount of Flash and RAM. 

To do this, you will spend at least $100-$200 on top of what you already paid for the 2600. In the case of the 2500, the latest version of the IOS that any 2500 series router can run is 12.3.x and even then it is only the IP PLUS IOS. To run the IP PLUS with IPSEC/VPN and FIREWALL, you have to go down to IOS version 12.2.

The CCNA exam really isn't that demanding when it comes to what the router needs but if you are going to buy a router to prep for the test, why not buy a router that you could actually use and has all the current features instead of one that.


What is the best router to use to learn the Cisco IOS? 

To me, the answer to this is the same as above. If you want to learn the Cisco IOS are you going to choose a simulator or a router that can't run the latest IOS or the latest features? No, you want to use a router that has the latest and greatest IOS and, most likely, get it at the lowest cost possible.

What is the best router to use to connect your home or small business to the Internet?

While the Cisco 800 series are more complex to configure when compared to a Linksys home/small business router, there is a reason for that. The reason is the number of higher-end features that are offered. Still, the 800 series does offer a decent graphical interface called SDM (deceivingly named, security device manager). 

In summary, the point of this article is to educate you on the best router to learn the Cisco IOS and use on small productions networks like your home or small office. The Cisco 800 series are the least expensive Cisco routers that run the full Cisco IOS. They also pack a ton of wireless, routing, and security features into a small package. While Cisco doesn't need my help to sell routers, I am recommending the 800 series Cisco router to those of you out there where it makes a good fit.

Wednesday, September 14, 2011

How to Transfer Switch Data

Cisco network switches include a feature that enables administrators to save configuration files to a network server once the switch configuration has been completed or modifications have been made to the configuration. Saving a backup of network switch configurations provides administrators with a quick reference of the switch configuration without having to connect to the switch, and also a "safety net" in the event that the configuration is damaged or lost. Transfer Cisco switch configuration data files to a TFTP server to store as a backup.

Things You'll Need

  • Microsoft Windows 7 computer TFTP service installed and telnet client enabled
  • Microsoft Windows 7 computer IP address
  • Cisco switch with telnet service enabled
  • IP address of the Cisco switch
  • Telnet password for the Cisco switch
  • Password for the Cisco switch Privilege Exec mode password
Steps to  Transfer Network Switch Data
1. Click "Start" on the Windows 7 computer PC desktop, click "Search" and then enter "cmd" in the "Search" box. Right-click the command line icon that displays in the upper left pane and select "Run as Administrator." Enter "telnet" in the command line window that appears, substituting the IP address of a Cisco router for the "" and then tap "Enter."
2. Type the telnet password and then press "Enter." Type "enable" and tap "Enter." Enter the Privilege Exec password when prompted and tap "Enter."

3. Type "copy nvram tftp://," except replace the "" with the IP address of the Windows 7 computer and replace "filename" with a name for the configuration file, and then tap "Enter." The switch configuration file has now been transferred to the Windows 7 computer TFTP service root directory.


Notes: There are more info about Cisco network switches such as Cisco switch selling, price of Cisco switches, Cisco switches' features and can visit