Router as a computer

Router as a computer

The basic purpose of a router is to route in and out from the source of information to its destination with specific addresses. Route works as computers that focus and specific in sending packets of data over the data network across the globe. Route have a special task and responsible for the purpose of interconnecting among networks by choosing the best path or route for a packet data to travel and forwarding packet data to their destination. Router is just like a postmaster of the network, where all needed information is available to the journey of the packet data from its source to its destination.

Routers works as the network center where all related information must pass through a specific route to ensure all packets data will be forwarded for its source to its destination correctly. In general routers have 2 obvious connections:

• WAN connection (involve public ISP)
• LAN connection


The main purpose of this router in the network is to ensure and examine the entire data packet’s passes through its and verify all of the data packets destination IP address, and finally determines the finest path by obtain the assist of a routing table. This mean that the final route will be determines by the most reliable route of the routing table.

Inside the router

Component Function
1 CPU Executes operating system instructions
2 Read-only memory (ROM) Holds diagnostic software used when router is powered up. Stores the router’s bootstrap program.
3 Non-volatile RAM (NVRAM) Stores startup configuration. This may include IP addresses (Routing protocol, Hostname of router)

4 Flash memory Contains the operating system (Cisco IOS)

5 Interfaces There exist multiple physical interfaces that are used to connect network.
6 Random access memory (RAM) Contains the running copy of configuration file. Stores routing table. RAM contents lost when power is off

Summary

 Routers are computers that specialize in sending data over a network.
 Routers are composed of:
-Hardware i.e. CPU, Memory, System bus, Interfaces
-Software used to direct the routing process
 IOS
 Configuration file
 Routers need to be configured. Basic configuration consists of:
-Router name
-Router banner
-Password(s)
-Interface configurations i.e. IP address and subnet mask
 Routing tables contain the following information
-Directly connected networks
-Remotely connected networks
-Network addresses and subnet masks
-IP address of next hop address

 Routers determine a packets path to its destination by doing the following
 Receiving an encapsulated frame & examining destination MAC address.
 If the MAC address matches then Frame is de-encapsulated so that router can examine the destination IP address.
 If destination IP address is in routing table or there is a static route then Router determines next hop IP address. Router will re-encapsulate packet with appropriate layer 2 frame and send it out to next destination.
 Process continues until packet reaches destination.
 Note - only the MAC addresses will change the source and destination IP addresses do not change.



Source : CISCO , CCNA2 Router and Routing Basic

Connection-Oriented Protocols:

Connection-Oriented Protocols:

The principally important characteristic of a connection oriented protocols is to facilitate a logical connection exist and recognized among two devices ahead of transferring a stream of data. Connection-oriented protocol might be present apply in the data link layers of the protocol stack or in the transport layers of the protocol stack, depending lying on the physical connections within place and the services essential via the system so as to be communicating.

Normally the achievements by subsequent a particular set of regulations that point out how a connection must be begin, talk, administer and terminated. Frequently it started with one host or device commences by sending a request to start a connection, and the other host or devices willpower respond. These hosts or devices resolve set the standard control information towards consent lying on and how the connection should be set up. If this is satisfying and victorious, data is sent between the hosts or devices. When it is done, the link willpower terminated.

Example of a connection-oriented protocol at the transport layer is the TCP protocol.

The communication sitting can be a circuit switched connection, or a virtual circuit connection within a packet switched network. For example the transport layer is the TCP protocol.

Simplex, Half-Duplex and Full Duplex Operation

Simplex, Half-Duplex and Full Duplex Operation


Simplex – The signal be sent away in unidirectional mode. This indicate the signal is sent away form the resource to the destination merely. The signal movements in single direction only. E.g. television or radio transmission.

Half-Duplex - Contrast to simplex communication, half duplex message authorized the traffic to travel in mutually directions. Half duplex merely approved the signal to pass through both direction but at the same time. This way that the signal have to be sent out first and finish the session as of a place and then simply the reception signal be able to be sent in and the session end from a station. Half duplex only authorized an only signal stream in one method or direction at an instant.

Full-Duplex transmission – It be able to function or effort in two-way course at a similar time. For the reason that of this, proficient full duplex enlarge the act of the networks. It can be sent and receive at the same without any problem. Full Duplex make use of two couple of wires where permit the station to transmit and obtain signal at any occasion. Full Duplex authorized he signal stream in mutually direction at the same time.

MAC addressing

MAC addressing short form of Media Access Control address. MAC provide the physical or devices or hardware address. MAC provide adrress on the network interface card (NIC), which located int the Layer 2 addresses. MAC address is very unique . The usual MAC addressing format is

XX:XX:XX:YY:YY:YY

Note ; XX:XX:XX = ID number of the adapter manufacture and

YY:YY:YY = serial number of manufacture. MAC address usually used the hexadecimal numbering format.

Network Interface Cards and Modem

The most important devices in networking , with them there will be not networking world

• NIC - Is a printed circuit board (PBC) that allows communication to and from a computer to the out side world. NIC requires Interrupt Request (IRQ), Input/Output (I/O), memory space and driver to perform it functions. Today NIC is simply installed to the computer. The plug and play concept is used to installed NIC driver. You only need to slot the NIC to the computer expansion slot and run the driver software and wait for successful result of the installation.

• Modem - A device that enable the computer to communicate to the world via telephony line. At this point, the modem will connect your computer to the outside virtually via Public Switched Telephone Network (PSTN). The function of a modem is to convert digital signal to an analog signal before entering the PSTN, then convert the analog signal to digital signal when the signal reaches its destination. Converting from digital to analog is known as modulation and analog to digital signal is known as demodulation. There are two types of modem communication: the first type known as asynchronous and the second type is known as the synchronous. Asynchronous communication means that the entire signal will be sent including specified character with control bits which consists of start bits and stop bits. These bits will differentiate between the starting bits and the ending bits. Synchronous communication means that the data will be sent out in blocks of bytes. This blocks of bytes is analyzed, verified and acknowledged by the computer on the destination side and it is asked to accept or reject the blocks. If rejected, the blocks are requested to be resent.

Remember this:

Network Interface Cards
1. Design within PCB
2. Usually use the plug and play methods
3. needs Interrupt Request (IRQ), Input/Output (I/O), memory space and a driver

Modems
1. Connect the outside virtually via Public Switched Telephone Network (PSTN).
2. convert digital signal to an analog signal before entering the PSTN
3. convert the analog signal to digital signal when the signal reaches its destination.
4. two types of modem : asynchronous modem and synchronous modem.

Networking and Internet connectivity

Introduction to Networking

What is networking? For sure you guys out there known about network! If not much but still you guys out there have some basic idea of networking.

This chapter will provide you general information’s what all is about of networking. Networking is something very wide. Starting with a computer, and makes it’s connecting to another computer throughout the world. From a simple network, it’s later become very huge computer networking know as the internet.


The Fundamentals of Internet Connectivity

What we can say about internet? Internet is like a multimillions of computers that are connected and gather together sharing information at the speed of light, perhaps. This means that internet was buildup via multimillions of computers in the globe. The internet nowadays are known as data networking, computer networking or others terms. But still internet started with a computer and connected to each other to become super computer connecting or networking.

The connection of the internet must start with physical connection, than logical connecting and finally the software applications. The physical connection are done from the PC to the network by network interface card (NIC) or modem, with special cable. The logical connection is a standard protocol to ensure the data flow that as required and planed. Some of this logical connection such as Transmission Control Protocol / Internet Protocol ( TCP/IP )
You will learn more detail about the TCP/IP chapter. Finally, the application will be interpreted as data and displayed as receiving information or data which in the form understandable manner.

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Application Layer

Application Layer

The application layer is the most upper layer in the TCP/IP model. This Application layer is use to operate high level protocols and problem of representations, encoding and dialog control. Application layer involving several applications such as file transfer, e-mail, remote login, network management, name management and used by the router. Some of applications that supported by TCP/IP were HTTP, TFTP, FTP, NFS, SMTP, Telnet, SNMP and DNS.

All application layer will functional to make sure the all data that applied at this layer will properly packaged for next layer function. In this application layer there other application program that is very useful in the networking. Some of the were netBIOS application, Windows sockets, Sockets and NetBIOS over TCP/IP.

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CCNA,CCNP,CCIE, TCP / IP , HTTP, TFTP , NFS, SMTP, Telnet, SNMP and DNS