Starting a Cisco Router

The Cisco will not come with a configuration saved when it is started. And when the start-up is completed then an initial software configuration is entered. A router should have an exact and valid configuration to operate on a network.

Initial Startup of a Cisco Router:

It should be required to verify the physical installation the router should be powered up and the cisco IOS software is to be console. And to start up a router certain operations are required the following are stated below.

• The power runs on self-test-POST to test the working of hardware system.
• According to the operating system the Cisco IOS Software finds and loads what the router requires
• Required configurations about router-specific attributes, interface addresses, and Protocol functions are installed.

When a Cisco router powers up, it performs a POST. During this process, the router will executes diagnostics to verify the working of CPU, interface circuits and its memory.

Completion on hardware check the router then proceeds for the software instalment’s where it finds and loads the Cisco IOS image, and then finds and loads the configuration file, if one exists.

The following steps are used for startup for a cisco router:

Step 1: Before starting the router, the following steps points should be verified

• Whether all the network cables are in secure connection.
• Whether the host terminal is connected to the console port
• Your console terminal application, such as HyperTerminal, is selected.

Step 2: The power switch is then is “On” or plug the device to power.

Step 3: The boot sequence should be observed and the Cisco IOS Software output on the console.

Initial Setup of a Cisco Router:

When the router starts up the device should be configured by automatically or by self and then setup is configured in the system. After a router is setup is completes the POST and loads a Cisco IOS image, it looks for a device configuration file called as NVRAM. This part of the router is a type of memory that retains its contents even when power is turned off in the router. And then if the router is enabled with password protection it should be logged in. 

 

                           

When starting a new Cisco router, if there was no certain required configuration file then the operating system will run the setup in the installation of the system configuration. 

Setup mode is not intended for entering complex protocol features in the router. Use setup mode to bring up a minimal configuration. Other various configurations can be used in order to setup the installation of the program to configure the router.

The main purpose of the setup configuration is to help the other type of routers which does not configure according to the OS in other sources. Setup mode can be done when the required configuration is not found, or it can be entered at any time after the router is operational or booted to the default, by entering the setup privileged in the EXEC mode command.

Constructing a Network Addressing Scheme

In all small network environments subnets which are also known as Subnetworks will segmenting into smaller divisions which have their own sort of IP address. In this some bits are used in host portion of an IP address in order to create a subnet address.

Subnetworks:

The networks are often divide into Subnetworks when there are in large networks to provide the addressing flexibility

In the subnet segments are hosts in the network itself. And without the subnet then the network will have a flat topology. Where it has short routing tables and relies on layer 2 MAC addresses to submit the packages. There was no hierarchical structure for the MAC addresses. Growth of the network leads to the use of the network bandwidth becomes less and less efficient.

The following are the disadvantages of the flat network:

• Layer 2 broadcast system is used by all the devices at the same time
• Bandwidth was shared among all the other devices which are on same network
• The lack of boundaries between the devices results in difficult to apply security policies.

The following are the advantages of subnetting a network:

• Performance can be improved when, Overall network traffic was reduced.
• It is easy to manage and map to geographical and functional requirements in the smaller networks.
• Network security can be applied through the interconnections between subnets than the entire network.

In a multiple network environments there is a connection in between Subnetworks and router which are connected to the internet. In the actual details of the internal the network is divided into several multiple Subnetworks which are inconsequential to other IP networks.

The IP addresses must provide an identification for both the network and the hosts of all devices.

Two-Level and Three-Level Addresses: 

In identifying the addresses by IPv4 method and there address classes was developed, a two- level address connection between network and host are seemed sufficient. Mask is associated with all the three address classes A, B, and C they are predefined on it, and it is not required to explicitly configure of the mask.

When the connected networks are increased, it will be clear that inefficient use of the network addresses. And to solve this problem a third level was introduced of addressing, subnets was developed.

Subnet Creation: 

This is created by taking the address bits from all the three cases host portion Class A, Class B, Class C. It is basically assigned by the network administrator. And in the same manner of the IP addresses they must be unique.

The powers of 2 are used in the algorithm to compute the number of subnets.

When the bits are borrowed from the host field, then the additional subnets are being created will be doubled at each certain time and one another is borrowed. While on bit is carried out one bit creates two more possible subnets (2¹=2) and the count goes on when bits are being borrowed.

• When 1 bit is used for the subnet filed then it is resulted in 2 possible subnets (2¹=2).
• When 2 bit is used for the subnet filed then it is resulted in 4 possible subnets (2²=4).
• When 3 bit is used for the subnet filed then it is resulted in 8 possible subnets (2³=8).
• When 4 bit is used for the subnet filed then it is resulted in 16 possible subnets (2⁴=16).
• When 5 bit is used for the subnet filed then it is resulted in 32 possible subnets (2⁵=32).
• When 6 bit is used for the subnet filed then it is resulted in 64 possible subnets (2⁶=64).

And in the general form the formulae can be stated as:

Number of subnets=2^s (where s is bits borrowed by the subnet).