NETWORKING CONCEPTS · · 2013-05-14NETWORKING CONCEPTS CET4773 | SPRING 2013 ... COMPUTER NETWORK? Transfer files from Computer to Computer ... (FTP) ask the underlying hardware

NETWORKING CONCEPTS CET4773 | SPRING 2013 | FINAL EXAM REVIEW | DR. MENDOZA

HOW DO COMPUTER NETWORKS WORK?

COMPUTER NETWORKS CONCEPTS

From CCENT/CCNA ICND1 640-822 Official Cert Guide, Third Edition by Wendell Odom, CCIE No. 1624 (ISBN: 1587204258) Copyright© 2012 Pearson Education, Inc.

Transfer data (files) from Computer to Computer (PC) Network interface card and media to connect PC How about more than two computers?


Figure 1-5 Star Cabling to a Repeater

HOW COMPUTER NETWORKS WORK Transfer files from Computer to Computer (PC) Network interface card and media to connect PC Hub repeats everything

What is the problem? How to solve it?


Figure 1-6 The First Network Addressing Convention

HOW COMPUTER NETWORKS WORK Transfer files from Computer to Computer (PC) Network interface card and media to connect PC Hub repeats everything

Unique numeric address on each networking card—a six byte number – Addressable How to deploy a network to multiply offices, floors, and buildings?


Figure 1-7 Per-Floor Hubs, Connected Together

THE FLINTSTONES NETWORK: THE FIRST COMPUTER NETWORK? Transfer files from Computer to Computer (PC) Network interface card and media to connect PC Hub repeats everything

Unique numeric address on each networking card—a six byte number – Addressable Use hubs –even better, use switches– to connect cables in a star topology. Numbers are not easy to remember

NAME/ADDRESS TABLE

SUMMARY UNTIL THIS POINT •  Ethernet networks use cards inside each computer.

•  The cards have unique numeric addresses •  Ethernet cables connect PCs to Ethernet hubs—hubs

that repeat each received signal out all other ports. •  The cabling is typically run in a star configuration—

in other words, all cables run from a cubicle to a wiring closet.

•  Applications such as the File Transfer Protocol (FTP) ask the underlying hardware to transfer the contents of files.

•  Users can use names—for instance, you might surf a website called www.certskills.com—but the name gets translated into the correct address.

TCP/IP AND OSI

NETWORKING MODELS

OBJECTIVES Networking Model Transmission Control Protocol/Internet Protocol (TCP/IP)

•  TCP •  IP

Open System Interconnection (OSI) reference model

Comparison of TCP/IP and OSI Model

NETWORKING MODEL

Networking Architecture or Networking Blueprint Comprehensive set of Documents

•  Protocols •  Physical requirement

Historically – Designed to prevent vendor specific networking solutions

TRANSMISSION CONTROL PROTOCOL/INTERNET PROTOCOL (TCP/IP) Defines and references a large collection of protocols that allow computers to communicate

•  Request for Comments •  Concept of Layers

PROTOCOLS (TCP/IP)

TRANSMISSION CONTROL PROTOCOL (TCP)

The TCP provides reliable transmission of data in an IP environment

•  TCP Connection Establishment •  Positive Acknowledgment and Retransmission (PAR) •  TCP Sliding Window •  TCP Packet Format

INTERNET PROTOCOL (IP) IP contains addressing information and some control information that enables packets to be routed

•  IP in RFC 791, represents the heart of the Internet •  IP has two primary responsibilities

•  providing connectionless, best-effort delivery of datagrams through an internetwork

•  providing fragmentation and reassembly of datagrams to support data links with different maximum-transmission unit (MTU) sizes

INTERNET PROTOCOL (IP) CONTINUED IP Packet Format

OPEN SYSTEM INTERCONNECTION (OSI) REFERENCE MODEL A 7 layer model, used extensively in early years of networking (1980’s) CCNA exam requires familiarity with each layer Used primarily to facilitate multivendor equipment interoperability Conceived and implemented by two international standards organizations

•  International Organization for Standardization (ISO) •  International Telecommunication Union–Telecommunications

Standards Sector (ITU-T)

OPEN SYSTEM INTERCONNECTION (OSI) REFERENCE MODEL (CONTINUED)

WAYS TO REMEMBER THE SEVEN LAYERS

All People Seem To Need Data Processing (Layers 7 to 1) Please Do Not Take Sausage Pizzas Away (Layers 1 to 7) Pew! Dead Ninja Turtles Smell Particularly Awful (Layers 1 to 7)

COMPARISON OF TCP/IP AND OSI MODEL

ENCAPSULATION

INTERACTION BETWEEN LAYERS

DATA

NETWORK DATA ENCAPSULATION

OSI MODEL SUMMARY

FUNDAMENTALS OF LANS

MODERN ETHERNET LAN

OBJECTIVES An Overview of Modern Ethernet LAN Carrier sense multiple access with collision detection (CSMA/CD) Ethernet UTP Cabling

•  Straight-Through •  Crossover

Introduction to Switches

Ethernet Data-Link Protocols

AN OVERVIEW OF MODERN ETHERNET LAN The Institute of Electrical and Electronics Engineers (IEEE) 802 series of protocols for Ethernet Data link layer, the IEEE separates the functions into two sub-layers:

•  The 802.3 Media Access Control (MAC) sub-layer •  The 802.2 Logical Link Control (LLC) sub-layer

Most of the standards define a different variation of Ethernet at the physical layer, with differences in speed and types of cabling.

AN OVERVIEW OF MODERN ETHERNET LAN

Today’s most common types of Ethernet


Figure 3-1 Typical Small Modern LAN

HISTORY


Figure 3-2 Small Ethernet 10BASE2 Network

CARRIER SENSE MULTIPLE ACCESS WITH COLLISION DETECTION (CSMA/CD) CSMA/CD logic helps prevent collisions and also defines how to act when a collision does occur.

•  A device with a frame to send listens until the Ethernet is not busy •  When the Ethernet is not busy, the sender(s) begin(s) sending the

frame. •  The sender(s) listen(s) to make sure that no collision occurred. •  If a collision occurs, the devices that had been sending a frame

each send a jamming signal to ensure that all stations recognize the collision.

•  After the jamming is complete, each sender randomizes a timer and waits that long before trying to resend the collided frame.

•  When each random timer expires, the process starts over

http://webmuseum.mi.fh-offenburg.de/index.php?view=exh&src=69

ALGORITHM

http://en.wikipedia.org/wiki/File:CSMACD-Algorithm.svg

ETHERNET UTP CABLING UTP cabling include either two or four pairs of wires. RJ45 Connectors and Ports

http://www.webopedia.com/TERM/U/UTP.html


RJ45 AND UTP

STRAIGHT-THROUGH CABLE

http://www.ertyu.org/steven_nikkel/ethernetcables.html

CROSSOVER CABLE


Figure 3-9 Typical Uses for Straight-Through and Crossover Ethernet Cables

A HUB


Figure 3-10 Hub Creates One Shared Electrical Bus

INTRODUCTION TO SWITCHES

FULL DUPLEX


Figure 3-12 Full-Duplex Operation Using a Switch

ETHERNET DATA-LINK PROTOCOLS Unique Physical address Burned into NIC

SUMMARY The four most popular types of Ethernet LANs and some details about each •  Ethernet •  Fast Ethernet •  Gigabit Ethernet (two types) The CSMA/CD logic Straight-through cable concept Crossover cable concept List of devices that transmit on wire pair 1,2 and pair 3,6 Structure of a unicast Ethernet address Key Ethernet addressing terms