Introduction to Netwrorking

What is Networking

when we talk we create special kind of vibration in the air to transfer our message to other person. same happens when mail somthing we write special patter in english on paper and send it.

Telegraphs are basis of data networking. in which we transfer message in english by first converting it into dashes and dots(mores code) then sending them on electrical wires and then this code is again converted back into the english language.

In data communication we are converting information from one type of mechanism of information to different patten and converting it back again.

Local Addressing

Categorizing Data Transmissions

GlobalPhone Number
mediaair and wire/wireless

Conversation Protocols

To call someone we have to go to some very some special process to talk to somebody, like picking up phone, network should be available, dial the number, wait for the phone to ring, then bell rings, other picks up the phone and then we start conversation


A set of rules used to move information between 2 people or devices.

Netwrok Protocols

Communication Model

Method of organizing information transfer into components.


Example of data is we are requesting a website and website which is literaly a document that we get from server in response to a request.

Cues / TCP

TCP role is cues.

  • first client computer send SYN synchronization message to server which means that “I want to make a connection to transfer data”

  • Server will respond with SYN-ACK synchronization acknowledge message. which means server is saying i am available for transfering data.

  • click will send ACK message, means that “Ok, i am about to send data.”

The above there message and responses is called three way handshake.

Three way handshake is used to establish a session to transfer a data.

Global / Internet Protocol (IP)

Ip is a global phone number that we assign to every system in the network. to send message to some computer we need to have the ip address of that computer.

We take the message and pack it with source and destination ip addresses.

Local / Ethernet


Ethernet Mac Address is identifier for ethernet communication locally.

We send message to router/default gateway using local adressing, when router receive message and it sees this message was sent using local addressing it throws aways local address and add the local adress of the next device that is connected to it locally. it will keep sending the packets locally, discarding the old local address and adding new addresses to get to the one router to the next router untill the message get to its destination… these all the local address are invisible to us for good reasons.



all the information/data, cues, ip and locall adres all is packaged up and sent via some kind of medium for examples, wire, wireless, fibre optics.

The OSI Model (Open system interconnect)

developed 1970

OSI Model vs TCP/IP model

TCP/IP ModelOSI Modelnill
Network InterfacePhysicalWires/Radio/Glass
Netwrok InterfaceData Link LayerEthernet
InternetNetworkInternet Protocol (IP)


Encapsulation is a corner stone for networking. we take the data from the application layer and put the chunk of it in to the transport layer to adressing








Data Networks and Addressing

When we have only one router in our network it automatically becomes our default gateway.

Local Addresses are at data link layer, Ethernet protcol operates here. addresses we use here are called mac addresses.(48bit number written in hexa-decimal)

  • mac address are factory burned onto the NIC(Network Interface Cards)

  • Mac Addresses have specific format, first 6 hexadecimal values or (24 bits) are manufacturer ID and other half part is called serial number.

Mac adress are supposed to be unique but it could happen that two devices have same mac address, it very unusual.

Purpose of Network Interface Card

Signal -> Frame


Physical Layer -> Data Link Layer

covert Signal to bit or bytes and frame and vice versa.

Addressing at Data Network Layer

Purpose of Routers

Without routers we can not tranfer packet from one network to another network.

Router seprates two distintc networks, router does this by havving two mac addresses, one is internal and one is external, internal is use to communicate with local network(network inside) and external mac address is used to communicate with internet(Network outside).

Side note only

When we create a frame frame is only allowed to communicate inside network, frame created on outside network must stay outside the network, has no choice. if we try to send the frame from inside network to outside network mainitaining its integrity it will be lost and thrown away.


to also see the mac addresses

ipconfig /all

Packet Internet Groper (PING)

ping is used to check if we can communicate with local or global networks. is the ip address of google dns server. ping -t dash t flag will fore the ping command to continue pinging that ip address. ping -t

CISCO Certifications

Enetry Level Associate Professional Expert Architect

Exam Objectives

CCNA Exam v1.0 (200-301)

Study for CCNA

Study Guides

  • Todd Lammele
  • Offical Curriculum Guide
  • Wendel Odom


  • Packet Tracer

Physical Lab Equipment

(3) Cisco 1841 Routers Routers should have serial interfaces on them os 15.1-4

(2) Cisco Catalyst 2960 Switches os 15.0-2

Layer 3 switch (1) Cisco Catalyst 3560 or 3750 Switch

Optional Layer 3 switches gives us more routers and lot of ports to work with

(2) Cisco Catalyst 3750 Switches

  • Switch Stack
  • OS 15.0-2