Notas ccent 1

CCENT Notes Part 1 – Networking Fundamentals

Ref : CCENT/CCNA ICND1 Official Exam Certification Guide, Second Edition by Wendell Odom

It is highly recommended that you read at least once the above study guide to make full use of this notes, it is expected that there may he minor errors in this notes, please always refer the study guide for accurate information.

(Jojo Jacob - CCENT)TABLE OF CONTENTS
Chapter 2 - The TCP/IP and OSI Networking Models........................................................3 Chapter 3 - Fundamentals of LANs.....................................................................................8 Chapter 4 - Fundamentals of WAN’s................................................................................20 Chapter 5 - Fundamentals of IPAddressing and Routing.................................................29 Chapter 6 - Fundamentals of TCP/IP Transport, Applications and Security.....................41

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Chapter 2 - The TCP/IP and OSI Networking Models
TCP/IP : Transmission Control Protocol/Internet Protocol OSI : Open System Interconnection RFC – Request for Comments TCP/IP Architecture Layers Application Transport InternetNetwork Access : HTTP, POP3, SMTP : TCP, UDP : IP : Ethernet, Frame Relay, PPP (WAN)

Application Layer : Provides interface between application software and the network, Provides network services to the applications. Transport Layer : (TCP/UDP) Guarantees the delivery of data across the network. TCP uses the mechanism of acknowledgements to guaranty the transmission of data across the network.Transport Layer header and its encapsulated data is called a SEGMENT Internet Layer : (IP) defines the IP Addressing and Routing.(the process of how a router should forward or route data packets) Internet Layer header and its encapsulated data, which includes Transport Layer, Application Layer header and any data is called IP Packet. Network Access Layer : defines the protocols and hardwaresrequired to deliver data across some physical network. Internet Layer (IP) uses the service of the Network Access Layer (Ethernet) to deliver IP Packets over a physical network. Network Access Layer’s encapsulated data are called FRAMES which includes network access layer (Ethernet, PPP) header, trailer and their encapsulated data. IP uses network access layer protocols (Ethernet. PPP) to deliverpackets to next router or host, in which IP packets will be encapsulated between Ethernet or PPP header and trailer for transmission over the physical medium as frames.

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Ethernet header and trailer may be striped and IP Packet may be encapsulated with PPP header and trailer during transmission depending on the network access protocol between the routers in the network. Same layer Interaction(different computers) : When a particular layer in one computer wants to communicate with the same layer in another computer, and this is done using headers which are transmitted between the computers. Adjacent Layer Interaction (same computer) : In a single computer one layer provides services to a higher layer. The software or hardware that implements the higher layer requests the lower layer toperform the task needed. Five Step Process of TCP/IP host sending data in a network. Step 1 : application data with application layer header. http ok message returned in a http header followed by content of the web page. Step 2 : encapsulate application layer data in a transport layer (tcp/udp) header Step 3 : encapsulate the transport layer data in a internet (IP) layer header Step 4 :encapsulate the data supplied by the internet layer into network access layer header and trailer. Step 5 : transmit the bits, physical layer encodes the signal onto a medium to transmit the frames Encapsulation : is the process of adding headers and trailers around data supplied by a higher level in the network model. Decapsulation : is the process of stripping (removing) the header and trailer from an...