Routing protocols

1.To understand routing protocol , just understand few terminology.
2.route,router,routed,routable,ad,as,igp,egp,metric.
3.Route:-is the network number(net id),which is carry by router from one network to another.it can be two types:-static and dynamic.
4.Router:-is the device which takes route from one place to another.
5.Routed/Routable:-is the packet contain by IP and which can carry over internet.
6.AD:-is the administrative distance which is used to find the trustworthiness of the route.it is define by the no.from 0-255. in which 0 is the best and 255 is bad.each routing protocol has its ad value.like:-directly connected = 0.static route=1.rip=120,eigrp=90,ospf=110.if all routing protocol is configured then lower no will be available in routing table.
7.AS:-autonomous system is the collection of routing protocol under single administrative domain(single company policy). there are two types of range of as.private and public.public range from 1-64511.private range from 64612-65535.

8.IGP:-is interior gateway protocol which run within the single autonomous system no.(distance vector,link state and hybrid protocol).
9.EGP:-is exterior gateway protocol which run between as like bgp.
10.Metric:-is the mathematical calculation used to find the best path.like:-hop,bandwidth,delay,cost etc.

IP Routing process

What is Routing:-
1.routing is the process of taking packet from one network to another.
2.this is done by routing protocol.
3.to work with routing protocol a router must need minimum information to select the best path.:destination address, source address,possible route to destination and shortest and best path to reach the destination.
4.Before to understand the working of routing protocol it is very important to understand how packet move from one network to another.

Host A want to send packet to Host B.:-
1.icmp protocol will make the echo request.(data payload).
2.icmp handover this echo to ip
3.ip then build up the packet.
4.At minimum ip contain source ip ,destination ip and protocol.
5.ip will check the destination address .
6.since destination is not local packet will go to default gateway.(router A)
7.mac address of router A should be resolved.this process is done by arp protocol.
8.once mac and ip resolved packet will send for framing.mac is used to provide access to media and frame will send to each device for error detection.once the frame process is complete packet is pulled from frame. and frame is discarded.
9.router will check the routing table for destination address.if found then process to next interface. if not found
message is sent by icmp that destination is not reachable.
10.now at exit interface packet again encapsulate with WAN technology like PPP frame. from router A source layer 2 will be router A exit interface. destination layer 2 will be router B incoming interface.where as layer 3 s and destination will remain the same.that is source layer 3 host A and destination layer 3 is host B.
11.now packet reach at router B. same process will occur here LAN technology is used with Ethernet frame.
12.now host b mac and ip should be resolved. if not arp process again resolve the addresses.
13.finally packet will reach at host B.
14.icmp will send the echo reply ack. if there is any problem then message will go request time out.this shows that packet while returning with ack having problem. check destination router. for solve the problem.
Focus on these points:-

Routing Process from Host A to Host B

(1) Host A to Switch A to Router A :

·                                 L2 Source Addr = MAC Host A

·                                 L2 Dest Addr = MAC Router A

·                                 L3 Source Addr = IP Host A

·                                 L3 Dest Addr = IP Host B

(2) Router A to Router B :

·                                 L2 Source Addr = MAC Router A

·                                 L2 Dest Addr = MAC Router B

·                                 L3 Source Addr = IP Host A

·                                 L3 Dest Addr = IP Host B

(3) Router B to Switch B to Host B :

·                                 L2 Source Addr = MAC Router B

·                                 L2 Dest Addr = MAC Host B

·                                 L3 Source Addr = IP Host A

·                                 L3 Dest Addr = IP Host B

Remember frame address(layer 2) change at each Link of router where as packet address( layer 3)remain the same.

Router booting process.

1.Start the router.
2.POST will run.(power on self test check the working conditions of component.if all well then),
3.bootstrap program will run and execute(it will find the location of IOS with the help of configuration register.)
4.default location is flash,tftp server and ROM.(config reg store in flash. it 2 byte in length.default no. is 0x2102.which  tells the default location of ios.
5.If IOS image found then load the IOS.
6.Ios find the configuration file.
7.there are two configuration file:-startup-config and running -config.
8.startup-config store in NVRAM.does not lost data when power is off.it is used to save the current running file.
9.if there is no information available then it will go in setup mode.this is user interactive mode ask question to configure the file.
10.Running-config file is used to store the current information.it is store the data in RAM.
Components of Router:-
1.ROM:-STORE POST,BOOTSTRAP PROGRAM AND MINI IOS.
2.FLASH:-STORE THE IOS IMAGE.AND CONFIG REGISTER.
3.NVRAM:-STORE THE STARTUP-CONFIG
4.RAM :---- STORE THE CURRENT INFORMATION WHICH IS NEED TO SAVE IN START-UP-CONFIG.OTHERWISE DATA WILL WE LOST WHEN ROUTER IS POWER OFF.

understand ethernet

Overview:-
1. It is LAN technology
2.It is shared media access method(contentions based)
3.It is originally developed by Dix.(DEC, Intel,xerox).
4.original standards are 10base2 and 10base5.(2means 200m and 5 means 500m cable.)
5.due to cable limitation new standard created by IEEE in 1980.(10baseT).
6.This is popularly known as Ethernet(802.3).
7.Then in the row fast Ethernet (base-TX,802.3u)gigabit Ethernet(1000base LX and SX,802.3z)gigabit Ethernet(1000 base T,802.3ab).
8 .Due to shared nature there may be chances of data collision (crash)
9.TO avoid data crash rule made that is CSMA/CD.
10.This rule force to device to work on half duplex.

Ethernet at Layer 2:-

1.AT layer 2 it divides in two sub layer:-LLC and MAC
2.LLC stands logical link control(802.2)
3.LLC provides communication with upper layer.IT frames the network layer packet.
4.MAC stands for Media access control(802.3).it  does frame delimiting .provides address and also does error detection.
Ethernet at layer 1:-
1.it does not communicate with upper layer.
2.it does not identify devices.
3.only Understand bit streams.
4.Physical standards operate on layer 1.

OSI MODEL

key points...................................
1.It is the certified model of ISO.
2.It is the reference model of data communication.
3.It divides the communication in smaller parts
4.It provide compatibility between different network vendor products.
5.It is divides the task into layers(seven layer)
6.Each layer does the specific task without affecting other layers
7.Each upper layer request the service from adjacent lower layer,in return lower layer provide service to upper layer.
8.Each layer after completing task add the header(encapsulation) which tells what is done by particular layer.called PDU.
9.Encapsulation is process of wrap the data in suitable technology which is understand by particular device.
10.Upper layer(7,6,5),makes data header.
11.layer 4 add segment header
12.layer 3 add packet header
13.layer 2 add frame header
14.layer 1 add bit &byte header.
Working of layer...........................
Application layer:-(7)
1.send data header
2.use service like http,ftp,telnet,smtp,dns,dhcp.
3.provide availability of resources
4.interface between user and application.
Presentation layer:-(6)
1.Maintain data format(jpeg,doc,xml etc)
2.provide service like encryption and compression.
Session Layer:-(5)
1.start and end the connection between application
2.use method like simplex,half duplex,full duplex.

Transport layer:-(4)
1.provide host to host communication
2.terminate virtual circuit
3.use tcp and udp service
4.provide error detection and correction.
5.add segment header.
Network layer:-(3)

1.provide network to network communication
2.provide path determination and selection
3.does routing
4.add packet header.
Data link Layer:-(2)
1.encapsulate the packet with frame header

2.provide error notification but not detection
3.provide upper layer interaction.(802.2)
4.provide physical addressing(802.3)
5.devices like switch nic,bridge work on it.
Physical Layer:-(1)
1.carry data over electronics signals
2.devices like hub repeater work on it.

Why we need network.

Key points to remember:-------------
1.It is the group of computer.
2.To share data and information.
3. To save time and money.
4. It use various application to do these above task. like Web browser,email,database and collaboration
How It work.
To Understand working of computer network.Just focus on terminology
1.LAN
2 Broadcast Domain.
3.Collision Domain
4. Network segmentation
5.OSI Model
6.TCP/IP model.

What is LAN.
1.It is the type of network which is situated in a single physical location.Like one building ,school etc.
2.It is base of WAN.
3.It Works on technology like Ethernet,token ring fddi etc. out of which Ethernet is most popular, because of it is easy to implement and  understand.

What is Broadcast Domain:-----

1.It is the area through which all the devices can listen and receive the data .

2. This is the message from single point to all directions.

3.For eg.: message from TV and radio.

4.Network device like switch is a single broadcast domain

5.Switch separate the collision domain. and provide network segmentation.

6.router separate the broadcast domain.

What is Collision Domain:---------

1.It is area where all devices try to access the same media.like single cable.

2.when multiple devices accessing the same media there may be chances of collision (data crash)

3.When collision occur no device can get the data.

4. This problem arise the need of new rule. so that we can protect data from crashing or conflicting.

5.Network device hub is called single collision device.

6.This device operate on the rule CSMA/CD.(carrier sense multiple access/collision detection.)

7.This rule work on the principle that one time only one device can transmit the data. in order to avoid data collision.

8.This communication method is called as Half duplex.(means one time only one device can transmit.like walky talky).  

Basic of network.

What is Network.
Today every one talking about networking in every field, whether it is concern with single person or it can be big
organization.
So what is networking.
Simple it is the process of creating network.Means when two or more things comes together to share their views
or ideas.called network.
ok now think like this.you want to talk with someone.how will you start.
Simple you need any medium through that you can send your voice.so when you talking with some one what medium you using that is air.because as per the human nature we need some one to share views.so this is beginning of the technology development.
Todays we are using computer network to share information and express their own views.Like i am using this blog to share my ideas.Simply i am going to talk about computer networking.
Computer network can carry any type of data,depends upon type of business.
There are basically four types of business environment:--1.HOME.2.SOHO.3.SMB.4.ENTERPRISE.
These environment can be identified by no. of users working  in these environment.For eg. in HOME there are only one user(one computer).In SOHO users from :2-10.In SMB from 11-250.In ENTERPRISE from 250-more. IN four business environment only three user class working.1.MIS PROFESSIONAL.SOFTWARE DEVELOPER 3. IT PROFESSIONALS/Engineering.
MIS PROFESSIONALS meaning all other than IT profession .like Managers,doctors,advocate,teachers,IAS etc.
IT PROFESSIONAL meaning who manage and maintain Computer network.
So to manage and maintain computer network we need to understand technology and terminology.Means what is network and how it work.TO understand any technology,just understand way to understand.like just focus on three points:-what,why and how.
WHAT means Introduction.
WHY means benefits.
How means functioning(working process).                                                                              
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