Some Topics That You Might Want To Pursue On Your Own That We Did Not Cover In This Article Are Listed Here The Work Described In This Article Is Mainly Focused On The Field Of “Broadcast Domains Vs Collision Domains" And Also Recap Of Ethernet Concept Only.
The Current Standard At The 10 Mbps Level Is 10baset. The "10" Stands For The Speed Of Transmission (10 Megabits Per Second); The "Base" Stands For "Baseband" Meaning It Has Full Control Of The Wire On A Single Frequency; And The "T" Stands For "Twisted Pair" Cable. Older Standards, Such As 10Base2 And 10Base5, Used Coaxial Cable, But These Standards Are Seldom Used In New Installations. Fiber Cable Can Also Be Used At This Level In 10Base FL.
What Is Network Cabling?
Cable Is The Medium Through Which Information Usually Moves From One Network Device To Another. There Are Several Types Of Cable Which Are Commonly Used With LANS. In Some Cases, A Network Will Utilize Only One Type Of Cable, Other Networks Will Use A Variety Of Cable Types. The Type Of Cable Chosen For A Network Is Related To The Network's Topology, Protocol, And Size. Understanding The Characteristics Of Different Types Of Cable And How They Relate To Other Aspects Of A Network Is Necessary For The Development Of A Successful Network.
The Following Sections Discuss The Types Of Cables Used In Networks And Other Related Topics.
◙ - ► 100Base FX - 100 Mbps Over Fiber Cable.
◙ - ► 100BaseSX -100 Mbps Over Multimode Fiber Cable.
◙ - ► 100BaseBX - 100 Mbps Over Single Mode Fiber Cable.
◙ - ► 1000Base T - 1000 Mbps Over 2-Pair Category 5 Or Better UTP Cable.
◙ - ► 1000Base TX - 1000 Mbps Over 2-Pair Category 6 Or Better UTP Cable.
◙ - ► 1000Base FX - 1000 Mbps Over Fiber Cable.
◙ - ► 1000Base SX -1000 Mbps Over Multimode Fiber Cable.
◙ - ► 1000Base BX - 1000 Mbps Over Single Mode Fiber Cable.
The Ethernet Standards Continue To Evolve. With 10 Gigabit Ethernet (10,000 Mbps) And 100 Gigabit Ethernet (100,000 Mbps),
Common Form Of LAN Uses Ethernet Which Is A Collection Of Standards And Specifications That Define Wiring And Signaling For The Network. There Are A Wide Variety Of Standards And Cable Types.
CATEGORY 2: Capable Of Transmitting Data At Speeds Up To 4 Megabits Per Second (Mbps).
CATEGORY 3 : Used In 10BASE-T Networks. Can Transmit Data At Speeds Up To 10 Mbps.
CATEGORY 4: Used In Token Ring Networks. Can Transmit Data At Speeds Up To 16 Mbps.
CATEGORY 5: Can Transmit Data At Speeds Up To 100 Mbps.
CATEGORY 5E: Used In Networks Running At Speeds Up To 1000 Mbps (1 Gigabit Per Second [GBPS]).
CATEGORY 6: Typically, Category 6 Cable Consists Of Four Pairs Of 24 American Wire Gauge (AWG) Copper Wires. Category 6 Cable Is Currently The Fastest Standard For UTP.
UNSHIELDED TWISTED PAIR (UTP): UTP Is A Cable Type That Consists Of Two Or More Insulated Copper Conductors In Which Each Pair Of Conductors Are Twisted Around Each Other. Category 1 UTP Cables Are Used For Telephony Connections. Category 3 And Higher Are Used For Ethernet LAN Connections. UTP Is Inexpensive And Easy To Work With.
SHIELDED TWISTED PAIR (STP): This Type Of Cable Is The Same As Unshielded Twisted Pair (UTP), Except That It Has Shielding Around It To Provide More Protection Against Electromagnetic Interference (EMI). Because Of Its Higher Cost, It Is Typically Only Used In Environments Where It Is Necessary.
FIBER OPTIC : Previously Only Used For Wan Connections, Fiber Optic Cabling Is Now Increasingly Being Used On LANs As Well For Its Capacity For Longer Distance And Higher Speeds. A Fiber-Optic System Is Similar To The Copper Wire System (UTP/STP), However, Fiber-Optics Use Light Pulses To Transmit Information Down Fiber Lines Instead Of Using Electronic Pulses To Transmit Information Down Copper Lines.
Fiber Cables Are Made Of Transparent Glass Or Plastic Fibers Which Allow Light To Be Guided From One End To The Other. There Are 2 Types Of Fiber Cabling - Single-Mode Fiber (SMF) And Multi-Mode Fiber (MMF). MMF Is The Most Common Type Used; However, SMF Can Support Longer Distances And Higher Speeds.
A CSU/DSU (Channel Service Unit/Data Service Unit) Is A Digital-Interface Device Used To Connect A Data Terminal Equipment Device Or DTE, Such As A Router, To A Digital Circuit, Such As A T-1 or T-3 connection Line.
◙ - ➤ DSU Is Responsible For Handling The Interface With The DTE.
A CSU/DSU Is The Equivalent Of The Modem For An Entire LAN. Contention Net Using CSMA/CD (Carrier Sense Multiple Access/Collision Detection) And A Backoff Algorithm When Collision Occur.
CSMA/CD - Carrier Sense Multiple Access Collision Detection Is A Network Access Method In Which Devices That Are Ready To Transmit Data First Check The Channel For A Carrier.
Ethernet Uses An Access Method Called CSMA/CD (Carrier Sense Multiple Access/Collision Detection). This Is A System Where Each Computer Listens To The Cable Before Sending Anything Through The Network.
If The Network Is Clear, The Computer Will Transmit. If Some Other Node Is Already Transmitting On The Cable, The Computer Will Wait And Try Again When The Line Is Clear.
Sometimes, Two Computers Attempt To Transmit At The Same Instant. When This Happens A Collision Occurs. Each Computer Then Backs Off And Waits A Random Amount Of Time Before Attempting To Retransmit. With This Access Method, It Is Normal To Have Collisions.
This Jam Signal Indicates To All Other Devices On The Ethernet Segment That There Has Been A Collision, And They Should Not Send Data Onto The Wire. ( CSMA/CD Works Bonding (AKA Link Aggregation, Port Trunking, Etherchannel, Etc.) - Uses Multiple Network Cables/Ports In Parallel To Increase The Link Speed Beyond The Limits Of Any One Single Cable Or Port, And To Increase The Redundancy For Higher Availability.)
In A Half Duplex Ethernet Network, A Collision Is The Result Of Two Devices On The Same Ethernet Network Attempting To Transmit Data At Exactly The Same Time. The Network Detects The "Collision" Of The Two Transmitted Packets And Discards Them Both.
Collisions Are A Natural Occurrence On Ethernets. Ethernet Uses Carrier Sense Multiple Access/ Collision Detect (CSMA/CD) As Its Method Of Allowing Devices To "Take Turns" Using The Signal Carrier Line.
Duplex Systems Are Employed In Many Communications Networks, Either To Allow For A Communication "Two-Way Street" Between Two Connected Parties Or To Provide A "Reverse Path" For The Monitoring And Remote Adjustment Of Equipment In The Field.
Another Major Advantage Of Full-Duplex Operation Is That The Maximum Segment Length Is No Longer Limited By The Timing Requirements Of Shared Channel Half-Duplex Ethernet. In Full-Duplex Mode, The Only Limits Are Those Set By The Signal-Carrying Capabilities Of The Media Segment. This Is Especially Useful For Fiber Optic Segments.
The Optional Full-Duplex Mode Is Specified In The 802.3x Supplement To The Standard, Which Formally Describes The Methods Used For Full-Duplex Operation. This Supplement Was Approved For Adoption Into The IEEE 802.3 Standard In March 1997. The 802.3x Supplement Also Describes An Optional Set Of Mechanisms Used For Flow Control Over Full-Duplex Links.
Collisions Occur When Two Devices Transmit At The Same Time. Devices Needed To Be Able To Detect And Recover From Collisions.
Each Device Could Either Transmit Or Receive Data At Any Given Time. This Meant That The Device Was Either Receiving Data Or Listening For Incoming Data. Devices Were Not Able To Both Send And Receive At The Same Time (Much Like Using A One-Lane Road For Traffic In Two Different Directions).
◙ Using Switches, Devices Are Given A Dedicated Communication Path. With A Single Device Connected To A Switch Port, Collisions Are Eliminated.
With These Problems Solved, You Can Turn Off Collision Detection. Devices Can Transmit And Receive Data Simultaneously, And Can Begin Transmitting Data As Soon As They Have Data To Send.
◙ - ➤ Devices With Collision Detection Turned On Operate In Half-Duplex Mode.
◙ - ➤ Devices with Collision Detection Turned off Operate In Full-Duplex Mode.
In Addition : The Lack Of Collisions Enables Switches To Communicate With Devices In Full-Duplex Mode. In A Full-Duplex Configuration, Devices Can Send And Receive Data From The Switch At The Same Time.
Contrast This With Half-Duplex Communication, In Which Communication Can Occur In Only One Direction At A Time. Full-Duplex Transmission Speeds Are Double That Of A Standard, Half-Duplex, Connection.
IN LAN Segmentation Is The Process Of Dividing The Network To Overcome Problems Such As Excessive Collisions, Broadcast Traffic, Or Heavy Network Traffic. By Segmenting A LAN, You Can Increase Network Performance, Maximize Bandwidth, And Reduce Congestion. As You Segment The Network, Need To Consider The Collision And Broadcast Domains On The Network.
Collision / Broadcast Domain Mainly Occurs In The Ethernet And It Can Mainly Be A Part Of The Segment Cable, Ethernet Hub Or The Whole Network Of Switches, Hubs And Other Devices. CSMA/CD Is An Efficient Way To Avoid The Collisions In The Network.
◙ - ► Collision Domains Are The Connected Physical Network Segments Where Collisions Can Occur. Any Network Or Subnetwork Where Devices Share The Same Transmission Medium And Where Packets Can Collide. Collisions Naturally Increase As The Number Of Devices In A Collision Domain Increase.
◙ - ► A Broadcast Domain Is A Group Of Collision Domains That Are Connected By Layer 2 Devices. One Message To Sent To All Devices As A Broadcast Message In A Broadcast Domain.
A Broadcast Domain Is A Logical Network Segment In Which Any Computer Connected To The Network Can Directly Transmit To Any Other In The Domain Without Having To Go Through A Routing Device, Providing They Share The Same Subnet And Gateway Address And Are In The Same VLAN
Note : A Special Condition Called A Broadcast Storm Happens When Broadcast Traffic Is Sent, Regenerated, And Responded To. In This Condition, The Amount Of Broadcast Traffic Consumes Network Bandwidth And Prevents Normal Communications. Faulty Devices Or Improper Configuration Conditions Can Lead To A Broadcast Storm.
Segmentation May Increase The Number Of Both The Collision And Broadcast Domains. Membership. Within Collision Or Broadcast Domains Differs Depending On The Connection Device Used.
◙ - ➤ Use A Bridge To Segment The Network (Divide Network Traffic) And To Provide Fault Tolerance.
◙ - ➤ Use A Switch To Reduce Collisions And Offer Guaranteed Bandwidth Between Devices.
◙ - ➤ Use A Router To Filter Broadcast Messages, Implement Security, Or Connect Different Networks.
Note :
LAN Segmentation And Design May Be Affected By The Types Of Applications And Protocols Running Over The Network. And The Main Differences Between Routers, Switches, And Bridges Are The Range Of Services Each Performs And The OSI Layer At Which They Operate.
FOR MORE REFERENCES :< /H2>◙ - ► FOR MORE ABOUT - > NETWORKING CONCEPTS:
◙ - ► All Devices Connected To The Hub Are In The Same Collision Domain.
◙ - ► All Devices Are In The Same (Only One) Broadcast Domain.
Note: Hub Is Not Able To Separate Broadcast Domain Like Switch Is. Routers On The Other Side Is Able To Separate Broadcast Domains (Only Router Can Break Up Broadcast Domains).
A Hub Does Not Perform Any Processing On The Data That It Forwards, Nor Does It Perform Any Error Checking. Ethernet Hubs Operate At Half-Duplex, Which Allows A Device To Either Transmit Or Receive Data, But Not Simultaneously. Ethernet Utilizes Carrier Sense Multiple Access With Collision Detect (CSMA/CD) To Control Media Access. Host Devices Monitor The Physical Link, And Will Only Transmit A Frame If The Link Is Idle.
However, If Two Devices Transmit A Frame Simultaneously, A Collision Will Occur. If A Collision Is Detected, The Hub Will Discard The Frames And Signal The Host Devices. Both Devices Will Wait A Random Amount Of Time Before Resending Their Respective Frames.
Remember, If Any Two Devices Connected To A Hub Send A Frame Simultaneously, A Collision Will Occur. Thus, All Ports On A Hub Belong To The Same Collision Domain. A Collision Domain Is Simply Defined As Any Physical Segment Where A Collision Can Occur.
◙ - ► Multiple Hubs That Are Uplinked Together Still All Belong To One Broadcast Domain.
◙ - ► Multiple Hubs That Are Uplinked Together Still All Belong To One Collision Domain. Increasing The Number Of Host Devices In A Single Collision Domain Will Increase The Number Of Collisions, Which Can Significantly Degrade Performance.
Also Hubs Belong To Only One (Single) Broadcast Domain A Hub Will Forward Both Broadcasts And Multicasts Out Every Port But The Originating Port. A Broadcast Domain Is A Logical Segmentation Of A Network, Dictating How Far A Broadcast (Or Multicast) Frame Can Propagate.
Note : Only A Layer-3 Device, Such As A Router, Can Separate Broadcast Domains.
◙ - ► All Devices Connected To A Single Port Are In The Same Collision Domain (Each Port Is Its Own Collision Domain).
◙ - ► All Devices Connected To The Bridge Or The Switch Are In The Same Broadcast Domain.
Note:
◙ - ➤ Layer 2 Devices Break Up The Collision Domain. For Above Example we Have 7 Devices Are Connected To A 12 Port Switch. Now, Each Of These Devices Are In A Separate Collision Domain. In Our Case Since We Have 7 Devices Or PC's Connected To 7 Switch Ports Then We Have Here 7 Collision Domains. The Switch Being A 12 Port One, It Can Provide Us With 12 Collision Domains.
Remember, ONE PORT ONE COLLISION DOMAIN, TWO PORT TWO COLLISION DOMAINS and so on.
◙ - ➤ Layer 2 Devices Fall Into The Category Of Being No Able To Break The Broadcast Domain. For Above Example We Have 7 Devices Connected To A Switch Make 7 Collision Domains Like We Saw Above But All The These Devices Are Still In One Broadcast Domain, BY DEFAULT. By Default Means That Right Out Of The Box The Switch Won't Divide The Broadcast Domain, However, You Can Configure VLAN's In Order For The Switch To Divide The BROADCAST DOMAIN.
Broadcast Domain : Layer 3 Devices By Default Are Capable Of Dividing The Broadcast Domain. No Configuration Is Required As Was The Case With Switches.
The Above Scenario When We Has 3 Devices Connected To A Router’s 3 Interfaces (Here I am Mention Only One Above Router), So We Got 3 Collision Domains And 3Broadcast Domains.
But Above ScenarioTotally we have 3 Broadcast Domains And 9 Collision Domains In Above Scenario.
◙ - ► Layer 3 Devices Such As Routers Break Up Broadcast Domains And Collision Domains.
◙ - ► All Devices Connected To A Single Interface Are In The Same Collision Domain (Each Individual Interface On A Router Belongs To Its Own Collision Domain).
Note : All Devices Accessible Through An Interface (Network) Are In The Same Broadcast Domain. Each Interface Represents Its Own Broadcast Domain If The Router Is Configured To Not Forward Broadcast Packets.
◙ - ➤ A Group Of Computers And Devices On A Network That Are Administered As A Unit With Common Rules And Procedures.
◙ - ➤ Defined As A Geographical Area Or Logical Area Where Anything In It Becomes Part Of The Domain. Also Domain Consists Of A Set Of Network Addresses.
◙ - ➤ On A Local Area Network (LAN), A Domain Is A Subnetwork Made Up Of A Group Of Clients And Servers Under The Control Of One Central Security Database.
Within A Domain, Users Authenticate Once To A Centralized Server Known As A Domain Controller, Rather Than Repeatedly Authenticating To Individual Servers And Services. Individual Servers And Services Accept The User Based On The Approval Of The Domain Controller. (Domain Controller (DC) Is A Server That Responds To Security Authentication Requests.
In A Half Duplex Ethernet Network, A Collision Is The Result Of Two Devices On The Same Ethernet Network Attempting To Transmit Data At Exactly The Same Time. The Network Detects The "Collision" Of The Two Transmitted Packets And Discards Them Both.
Collisions Are A Natural Occurrence On Ethernets. Ethernet Uses Carrier Sense Multiple Access/ Collision Detect (CSMA/CD) As Its Method Of Allowing Devices To "Take Turns" Using The Signal Carrier Line.
When A Device Wants To Transmit, It Checks The Signal Level Of The Line To Determine Whether Someone Else Is Already Using It. If It Is Already In Use, The Device Waits And Retries, Perhaps In A Few Seconds. If It Isn't In Use, The Device Transmits. However, Two Devices Can Transmit At The Same Time In Which Case A Collision Occurs And Both Devices Detect It. Each Device Then Waits A Random Amount Of Time And Retries Until Successful In Getting The Transmission Sent.
In A Collision Domain, A Frame Sent By A Device Can Cause Collision With A Frame Sent By Another Device In The Same Collision Domain. Moreover, A Device Can Hear The Frames Destined For Any Device In The Same Collision Domain.
Basically, A Collision Domain Is A Network Segment That Allows Normal Network Traffic To Flow Back And Front. In The Old Days Of Hubs, This Meant You Had A Lot Of Collisions, And The Old CSMA/CD Would Be Working Overtime To Try To Get Those Packets Re-Sent Every Time There Was A Collision On The Wire (Since Ethernet Allows Only One Host To Be Transmitting At Once Without There Being A Traffic Jam). With Switches, You Break Up Collision Domains By Switching Packets Bound For Other Collision Domains. These Days, Since We Mostly Use Switches To Connect Computers To The Network, You Generally Have One Collision Domain To A Pc.
Broadcast Domains Are Exactly What They Imply: They Are Network Segments That Allow Broadcasts To Be Sent Across Them.
Since Switches And Bridges Allow For Broadcast Traffic To Go Unswitched, Broadcasts Can Traverse Collision Domains Freely.
The Simple Way To Look At It Is This Way: Switches Break Up Collision Domains, While Routers (And VLANS) Break Up Collision Domains And Broadcast Domains. Also, A Broadcast Domain Can Contain Multiple Collision Domains, But A Collision Domain Can Never Have More Than One Broadcast Domain Associated With It.
A Hub Also Doesn’t Understand Anything About IP Addresses, So When The Signal Is Received By A Port On The Hub, It's Job Is To Send That Signal To Every Other Device Plugged Into It (On All Ports), This Means That If A Pc Sent A Broadcast Message, All Devices Would Receive It.
Note:The Big Thing To Understand Here, Is That A Hub Does Create A Single Broadcast And Collision Domain.
Each Port On A Switch Will Be Its Own Collision Domain (Assuming The Port Has Been Configured As Half-Duplex), In A Case Where Each Port Has Been Configured As Full-Duplex No Collisions Should Ever Occur. This Means That A Switch Creates Collision Domains (1 Per Port, In Theory).
A Switch However Does Not Understand IP Addresses (Assuming This Is A Standard Switch, And Not A Layer 3 Switch Or Multilayer Switch) And Therefore Doesn’t Understand Broadcast Messages. This Means That When A Broadcast Is Sent From A Host Attached To The Switch It Will Send The Traffic To All Ports. Since All Machines On The Switch Will Receive The Broadcast Message, So They Are Said To Be In The Same Broadcast Domain.
Hubs Are Layer-1 Devices That Physically Connect Network Devices Together For Communication. Hubs Can Also Be Referred To As Repeaters.
Hubs Provide No Intelligent Forwarding Whatsoever. Hubs Are Incapable Of Processing Either Layer-2 Or Layer-3 Information, And Thus Cannot Make Decisions Based On Hardware Or Logical Addressing.
Thus, Hubs Will Always Forward Every Frame Out Every Port, Excluding The Port Originating The Frame. Hubs Do Not Differentiate Between Frame Types, And Thus Will Always Forward Unicasts, Multicasts, And Broadcasts Out Every Port But The Originating Port.
Ethernet Hubs Operate At Half-Duplex, Which Allows A Device To Either Transmit Or Receive Data, But Not Simultaneously. Ethernet Utilizes Carrier Sense Multiple Access With Collision Detect (CSMA/CD) To Control Media Access. Host Devices Monitor The Physical Link, And Will Only Transmit A Frame If The Link Is Idle.
However, If Two Devices Transmit A Frame Simultaneously, A Collision Will Occur. If A Collision Is Detected, The Hub Will Discard The Frames And Signal The Host Devices. Both Devices Will Wait A Random Amount Of Time Before Resending Their Respective Frames.
Remember, If Any Two Devices Connected To A Hub Send A Frame Simultaneously, A Collision Will Occur. Thus, All Ports On A Hub Belong To The Same Collision Domain. A Collision Domain Is Simply Defined As Any Physical Segment Where A Collision Can Occur.
Multiple Hubs That Are Uplinked Together Still All Belong To One Collision Domain. Increasing The Number Of Host Devices In A Single Collision Domain Will Increase The Number Of Collisions, Which Can Significantly Degrade Performance.
Hubs Also Belong To Only One Broadcast Domain – A Hub Will Forward Both Broadcasts And Multicasts Out Every Port But The Originating Port. A Broadcast Domain Is A Logical Segmentation Of A Network, Dictating How Far A Broadcast (Or Multicast) Frame Can Propagate.
Note:Only A Layer-3 Device, Such As A Router, Can Separate Broadcast Domains.
◙ - ► A Collision Domain Is A Section Of Network Where Packet Collisions Can Occur If Two Nodes Attempt To Communicate At The Same Time (Is Defined As A Single CSMA/CD Network Segment In Which There Will Be A Collision If Two Computers Attached To The System Both Transmit At The Same Time / Only One Device Is Able To Transmit The Data At The Same Time.).
◙ - ► A Broadcast Domain Includes All Of The Hosts That A Broadcast Frame Transmitted By A Single Host Can Reach (Is A Logical Division Of A Computer Network, In Which All Nodes Can Reach Each Other By Broadcast).
◙ - ► In A Collision Domain, A Frame Sent By A Device Can Cause Collision With A Frame Sent By Another Device In The Same Collision Domain.
◙ - ► In A Broadcast Domain, A Broadcast Frame Sent By A Device Can Be Received By All Other Devices In The Same Broadcast Domain.
◙ - ► In A LAN Segment Or An Ethernet Network Segment Consists Of The Devices Connected With A Coaxial Cable Or A Hub. The Devices Are In The Same Collision Domain.
◙ - ► As Routers Do Not Pass Broadcast Traffic, They Form A Boundary Of A Broadcast Domain.
◙ - ► All Hosts In A Broadcast Domain Share A Common Layer 3 Network Address. In TCP/IP Terminology This Means That They Are On The Same Subnet.
◙ - ► Routers Break Up Broadcast Domains And Bridges Break Up Collision Domains. Routers Also Break Up Collision Domains.
◙ - ► Routers Manage Traffic At Layer 3. Routers Can Be Configured Statically Or Dynamically. Dynamically Configured Routers Can Adjust To Changing Network Conditions.
◙ - ► So Switch Creates Separate Collision Domains And Router Creates Separate Broadcast Domains. All Ports Of Hub Are One Collision Domain
◙ - ► On Switched Networks, Routers Break Up Broadcast Domains, And Every Switch Port Is Its Own Separate Collision Domain.
◙ - ► Switches Manage Traffic At Layer 2. Some Switches Have Layer 3 And 4 Functionality, But Are Not As Suited As Routers To Managing Traffic Above Layer 3. Switches Can Use Store And Forward, Cut Through Or Fragment Free Switching Methods.
◙ - ► VLANS Allow Separate Broadcast Domains To Be Located On A Single Switch.
A Virtual LAN (VLAN) Is A Broadcast Domain Created Based On The Functional, Security, Or Other Requirements, Instead Of The Physical Locations Of The Devices, On A Switch Or Across Switches. With VLANS, A Switch Can Group Different Interfaces Into Different Broadcast Domains. Without VLANS, All Interfaces Of A Switch Are In The Same Broadcast Domain; Switches Connected With Each Other Are Also In The Same Broadcast Domain, Unless There Is A Router In Between. .
CSMA/CD: - Carrier Sense Multiple Access Collision Detection Is A Network Access Method In Which Devices That Are Ready To Transmit Data First Check The Channel For A Carrier. If No Carrier Is Sensed, A Device Can Transmit. If Two Devices Transmit At Once, A Collision Occurs And Each Computer Backs Off And Waits A Random Amount Of Time Before Attempting To Retransmit. This Is The Access Method Used By Ethernet.
Coaxial Cable: - Cable Consisting Of A Single Copper Conductor In The Center Surrounded By A Plastic Layer For Insulation And A Braided Metal Outer Shield.
10Base2: - Ethernet Specification For Thin Coaxial Cable, Transmits Signals At 10 Mbps (Megabits Per Second) With A Distance Limit Of 185 Meters Per Segment.
10Base5: - Ethernet Specification For Thick Coaxial Cable, Transmits Signals At 10 Mbps (Megabits Per Second) With A Distance Limit Of 500 Meters Per Segment.
10Base F: - Ethernet Specification For Fiber Optic Cable, Transmits Signals At 10 Mbps (Megabits Per Second) With A Distance Limit Of 2000 Meters Per Segment.
10Base T: - Ethernet Specification For Unshielded Twisted Pair Cable (Category 3, 4, Or 5), Transmits Signals At 10 Mbps (Megabits Per Second) With A Distance Limit Of 100 Meters Per Segment.
100Base T: - Ethernet Specification For Unshielded Twisted Pair Cabling That Is Used To Transmit Data At 100 Mbps (Megabits Per Second) With A Distance Limit Of 100 Meters Per Segment.
1000Base TX: - Ethernet Specification For Unshielded Twisted Pair Cabling That Is Used To Trasmit Data At 1 Gbps (Gigabits Per Second) With A Distance Limitation Of 220 Meters Per Segment.
Gigabit Ethernet : - An Ethernet Protocol That Raises The Transmission Rates To 1 Gbps (Gigabits Per Second). It Is Primarily Used For A High Speed Backbone Of A Network.
GigaByte (GB): - One Billion Bytes Of Information. One Thousand Megabytes.
Fast Ethernet: - A New Ethernet Standard That Supports 100 Mbps Using Category 5 Twisted Pair Or Fiber Optic Cable.
Fiber Distributed Data Interface (FDDI): - A Network Protocol That Is Used Primarily To Interconnect Two Or More Local Area Networks, Often Over Large Distances.
Fiber Optic Cable: - A Cable, Consisting Of A Center Glass Core Surrounded By Layers Of Plastic, That Transmits Data Using Light Rather Than Electricity. It Has The Ability To Carry More Information Over Much Longer Distances.
†
The Goal Of This Article Is To Give An Easy Way To Understand The “Broadcast Domains Vs Collision Domains". Hope This Article Will Help Every Beginners Who Are Going To Start Cisco Lab Practice Without Any Doubts.
Some Topics That You Might Want To Pursue On Your Own That We Did Not Cover In This Article Are Listed Here, Thank You And Best Of Luck.
This Article Written Author By: Premakumar Thevathasan. CCNA, CCNP, CCIP, MCSE, MCSA, MCSA - MSG, CIW Security Analyst, CompTIA Certified A+.
This Document Carries No Explicit Or Implied Warranty. Nor Is There Any Guarantee That The Information Contained In This Document Is Accurate. Every Effort Has Been Made To Make All Articles As Complete And As Accurate As Possible.
It Is Offered In The Hopes Of Helping Others, But You Use It At Your Own Risk. The Author Will Not Be Liable For Any Special, Incidental, Consequential Or Indirect Any Damages Due To Loss Of Data Or Any Other Reason That Occur As A Result Of Using This Document. But No Warranty Or Fitness Is Implied. The Information Provided Is On An "As Is" Basic. All Use Is Completely At Your Own Risk.
FIRST RECAP OF ETHERNET CONCEPT
ETHERNET :
The Original Ethernet Standard Was Developed In 1983 And Had A Maximum Speed Of 10 Mbps At The Time. The Ethernet Protocol Allows For Bus, Star, Or Tree Topologies, Depending On The Type Of Cables Used And Other Factors.FAST ETHERNET :
The Fast Ethernet Protocol Supports Transmission Up To 100 Mbps. Fast Ethernet Requires The Use Of Different, More Expensive Network Concentrators/Hubs And Network Interface Cards. In Addition, Category 5 Twisted Pair Or Fiber Optic Cable Is Necessary.NETWORK CABLING :
Cable - Transmission Medium Of Copper Wire Or Optical Fiber Wrapped In A Protective Cover.FAST ETHERNET STANDARDS INCLUDE :
◙ - ► 100Base T - 100 Mbps Over 2-Pair Category 5 Or Better UTP Cable.GIGABIT ETHERNET :
Gigabit Ethernet Standard Is A Protocol That Has A Transmission Speed Of 1 GBPs (1000 Mbps). It Can Be Used With Both Fiber Optic Cabling And Copper. The 1000Base T, The Copper Cable Used For GigaBit.COMMONLY USED TYPES OF UTP CABLING ARE AS FOLLOWS :
CATEGORY 1: Used For Telephone Communications. Not Suitable For Transmitting Data.THE MOST COMMON CABLE TYPES ARE DISCUSSED BELOW:
COAXIAL : Older Ethernet Technologies Such As 10Base5 And 10Base2 Used Coaxial Cable (RG-58). These Network Types Are No Longer In Use. This Type Of Network Connection Has Made A Recent Comeback And Is Being Used For Broadband Cable Internet Connections (RG-59).CSU/DSU
THE CSU/DSU IMPLEMENTS TWO DIFFERENT FUNCTIONS :
◙ - ➤ CSU Is Responsible For The Connection To The Telecom Network.CSMA/CD
ALSO, CSMA/CA:
Carrier Sense Multiple Access Collision Avoidance Is A Network Access Method In Which Each Device Signals Its Intent To Transmit Before It Actually Does So. This Prevents Other Devices From Sending Information, Thus Preventing Collisions From Occurring Between Signals From Two Or More Devices. This Is The Access Method Used By Localtalk.HALF DUPLEX & FULL DUPLEX
WHAT IS DUPLEX:
A Duplex Communication System Is A Point-To-Point System Composed Of Two Connected Parties Or Devices That Can Communicate With One Another In Both Directions.HALFDUPLEX :
A Half-Duplex System Provides Communication In Both Directions, But Only One Direction At A Time (Not Simultaneously). Typically, Once A Party Begins Receiving A Signal, It Must Wait For The Transmitter To Stop Transmitting, Before Replying (Antennas Are Of Trans-Receiver Type In These Devices, So As To Transmit And Receive The Signal As Well). A Half-Duplex Fast Ethernet Twisted-Pair Segment Provides A Maximum Of 100 Mbps Of Bandwidth.FULLDUPLEX :
In Full-Duplex Operation, A Connection Between Two Devices Is Capable Of Sending Data In Both Directions Simultaneously. When Operated In Full-Duplex, The Same 100BASE-TX Twisted-Pair Segment Can Provide A Total Bandwidth Of 200 Mbps.THESE TWO PROBLEMS WERE SOLVED IN THE FOLLOWING WAYS :
◙ Using Twisted Pair Cable, Multiple Strands Of Wires Are Combined Into A Single Cable. Devices Can Use Different Wires To Send And Receive Data (Allowing Them To Do Both Simultaneously).Contrast This With Half-Duplex Communication, In Which Communication Can Occur In Only One Direction At A Time. Full-Duplex Transmission Speeds Are Double That Of A Standard, Half-Duplex, Connection.
IN LAN Segmentation Is The Process Of Dividing The Network To Overcome Problems Such As Excessive Collisions, Broadcast Traffic, Or Heavy Network Traffic. By Segmenting A LAN, You Can Increase Network Performance, Maximize Bandwidth, And Reduce Congestion. As You Segment The Network, Need To Consider The Collision And Broadcast Domains On The Network.
IN GENERAL :
FOR MORE REFERENCES :< /H2>◙ - ► FOR MORE ABOUT - > NETWORKING CONCEPTS:
◙ - ► FOR MORE ABOUT - > ETHERNET TECHNICAL OVERVIEW :
◙ - ► FOR MORE ABOUT - > BASIC INFORMATION ON LAN SWITCHING :
◙ - ► FOR MORE ABOUT - > DIFFERENCE IN BETWEEN ROUTER, SWITCH (LAYER 2 & LAYER 3), BRIDGE AND HUB:
HOW TO COUNT COLLISION DOMAIN AND BROADCAST DOMAIN
◙ - ➤ A COLLISION DOMAIN IS A LOGICAL NETWORK SEGMENT WHERE DATA PACKETS CAN “COLLIDE” WITH ONE ANOTHER FOR BEING SENT ON A SHARED MEDIUM, IN PARTICULAR IN THE ETHERNET NETWORKING PROTOCOL.
◙ - ➤ A BROADCAST DOMAIN IS A LOGICAL NETWORK SEGMENT IN WHICH ANY COMPUTER CONNECTED TO THE NETWORK CAN DIRECTLY TRANSMIT TO ANY OTHER IN THE DOMAIN WITHOUT HAVING TO GO THROUGH A ROUTING DEVICE, PROVIDING THEY SHARE THE SAME SUBNET AND GATEWAY ADDRESS AND ARE IN THE SAME VLAN, (DEFAULT OR INSTALLED).
DEVIES: HUP LAYER - 1 PHYSICAL LAYER :
However, If Two Devices Transmit A Frame Simultaneously, A Collision Will Occur. If A Collision Is Detected, The Hub Will Discard The Frames And Signal The Host Devices. Both Devices Will Wait A Random Amount Of Time Before Resending Their Respective Frames.
Remember, If Any Two Devices Connected To A Hub Send A Frame Simultaneously, A Collision Will Occur. Thus, All Ports On A Hub Belong To The Same Collision Domain. A Collision Domain Is Simply Defined As Any Physical Segment Where A Collision Can Occur.
◙ - ► Multiple Hubs That Are Uplinked Together Still All Belong To One Broadcast Domain.
Note : Only A Layer-3 Device, Such As A Router, Can Separate Broadcast Domains.
DEVIES: BRIDGES / SWTICHES LAYER 2 - DATA LINK LAYER :
DEVIES: ROUTERS / LAYER 3 SWITCHES, LAYER – 3 NETWORK LAYER :
Collision Domain: Layer 3 Devices Are Similar To Layer 2 Ones As They Are Capable Of Dividing The Collision Domain. 2 Devices Connected To Router Are In 2 Separate Collision Domains.
UNDERSTANDS THE KEY DIFFERENCES IN BETWEEN BROADCAST DOMAINS AND COLLISION DOMAINS
FIRST KNOW WHAT IS DOMAIN :
◙ - ➤ A Group Of Computers And Devices On A Network That Are Administered As A Unit With Common Rules And Procedures.
◙ - ➤ Defined As A Geographical Area Or Logical Area Where Anything In It Becomes Part Of The Domain. Also Domain Consists Of A Set Of Network Addresses.
◙ - ➤ On A Local Area Network (LAN), A Domain Is A Subnetwork Made Up Of A Group Of Clients And Servers Under The Control Of One Central Security Database.
Within A Domain, Users Authenticate Once To A Centralized Server Known As A Domain Controller, Rather Than Repeatedly Authenticating To Individual Servers And Services. Individual Servers And Services Accept The User Based On The Approval Of The Domain Controller. (Domain Controller (DC) Is A Server That Responds To Security Authentication Requests.
WHAT IS COLLISION :
◙ - ➤ The Situation That Occurs When Two Or More Devices Attempt To Send A Signal Along The Same Channel At The Same Time.In A Half Duplex Ethernet Network, A Collision Is The Result Of Two Devices On The Same Ethernet Network Attempting To Transmit Data At Exactly The Same Time. The Network Detects The "Collision" Of The Two Transmitted Packets And Discards Them Both.
Collisions Are A Natural Occurrence On Ethernets. Ethernet Uses Carrier Sense Multiple Access/ Collision Detect (CSMA/CD) As Its Method Of Allowing Devices To "Take Turns" Using The Signal Carrier Line.
When A Device Wants To Transmit, It Checks The Signal Level Of The Line To Determine Whether Someone Else Is Already Using It. If It Is Already In Use, The Device Waits And Retries, Perhaps In A Few Seconds. If It Isn't In Use, The Device Transmits. However, Two Devices Can Transmit At The Same Time In Which Case A Collision Occurs And Both Devices Detect It. Each Device Then Waits A Random Amount Of Time And Retries Until Successful In Getting The Transmission Sent.
COLLISION DOMAIN VS BROADCAST DOMAIN
COLLISION DOMAIN :
If Two Devices Within The Domain Attempt To Transmit Simultaneously The Packets Will Collide And Retransmission Will Occur.In A Collision Domain, A Frame Sent By A Device Can Cause Collision With A Frame Sent By Another Device In The Same Collision Domain. Moreover, A Device Can Hear The Frames Destined For Any Device In The Same Collision Domain.
Basically, A Collision Domain Is A Network Segment That Allows Normal Network Traffic To Flow Back And Front. In The Old Days Of Hubs, This Meant You Had A Lot Of Collisions, And The Old CSMA/CD Would Be Working Overtime To Try To Get Those Packets Re-Sent Every Time There Was A Collision On The Wire (Since Ethernet Allows Only One Host To Be Transmitting At Once Without There Being A Traffic Jam). With Switches, You Break Up Collision Domains By Switching Packets Bound For Other Collision Domains. These Days, Since We Mostly Use Switches To Connect Computers To The Network, You Generally Have One Collision Domain To A Pc.
BROADCAST DOMAIN :
In A Broadcast Domain, A Broadcast Frame Sent By A Device Can Be Received By All Other Devices In The Same Broadcast Domain.Broadcast Domains Are Exactly What They Imply: They Are Network Segments That Allow Broadcasts To Be Sent Across Them.
Since Switches And Bridges Allow For Broadcast Traffic To Go Unswitched, Broadcasts Can Traverse Collision Domains Freely.
ROUTERS, HOWEVER, DON'T ALLOW BROADCASTS THROUGH BY DEFAULT,
So When A Broadcast Hits A Router (Or The Perimeter Of A VLAN), It Doesn't Get Forwarded.The Simple Way To Look At It Is This Way: Switches Break Up Collision Domains, While Routers (And VLANS) Break Up Collision Domains And Broadcast Domains. Also, A Broadcast Domain Can Contain Multiple Collision Domains, But A Collision Domain Can Never Have More Than One Broadcast Domain Associated With It.
A HUB CREATES A COLLISION DOMAIN AND A BROADCAST DOMAIN.
Here Is The Theory Behind It. Since A Hub Is A Layer 1 Device And Runs At Half-Duplex, There Is Always The Chance (More Like A Guarantee) That There Will Be Collisions. It Doesn’t Matter How Many Pc's Are Plugged Into The Hub They Will All Be Affected By The Same Collision Path And Hence All Part Of The Same Collision Domain Which Was Created Due To The Fact They Were Plugged Into The Hub.A Hub Also Doesn’t Understand Anything About IP Addresses, So When The Signal Is Received By A Port On The Hub, It's Job Is To Send That Signal To Every Other Device Plugged Into It (On All Ports), This Means That If A Pc Sent A Broadcast Message, All Devices Would Receive It.
Note:The Big Thing To Understand Here, Is That A Hub Does Create A Single Broadcast And Collision Domain.
A LAYER 2 SWITCH IS A DEVICE:
Which Means It Has Some Intelligence In The Form Of Learning Mac Addresses. This Means That When A Pc With Mac Address 'A' Wants To Send Data To A Pc With Mac Address 'B' The Switch Will Only Send The Data To The Corresponding Port. This Means That Multiple Pc's Could Have Conversations At The Same Time. Switches Also Make Use Of Buffers Which Allow Data To Be Held Back And Sent When The Line Is Free And Hence Prevents Any Collisions From Occurring.Each Port On A Switch Will Be Its Own Collision Domain (Assuming The Port Has Been Configured As Half-Duplex), In A Case Where Each Port Has Been Configured As Full-Duplex No Collisions Should Ever Occur. This Means That A Switch Creates Collision Domains (1 Per Port, In Theory).
A Switch However Does Not Understand IP Addresses (Assuming This Is A Standard Switch, And Not A Layer 3 Switch Or Multilayer Switch) And Therefore Doesn’t Understand Broadcast Messages. This Means That When A Broadcast Is Sent From A Host Attached To The Switch It Will Send The Traffic To All Ports. Since All Machines On The Switch Will Receive The Broadcast Message, So They Are Said To Be In The Same Broadcast Domain.
IN HUB :
A Hub Is The Simplest Of These Devices. Any Data Packet Coming From One Port Is Sent To All Other Ports.Hubs Are Layer-1 Devices That Physically Connect Network Devices Together For Communication. Hubs Can Also Be Referred To As Repeaters.
Hubs Provide No Intelligent Forwarding Whatsoever. Hubs Are Incapable Of Processing Either Layer-2 Or Layer-3 Information, And Thus Cannot Make Decisions Based On Hardware Or Logical Addressing.
Thus, Hubs Will Always Forward Every Frame Out Every Port, Excluding The Port Originating The Frame. Hubs Do Not Differentiate Between Frame Types, And Thus Will Always Forward Unicasts, Multicasts, And Broadcasts Out Every Port But The Originating Port.
Ethernet Hubs Operate At Half-Duplex, Which Allows A Device To Either Transmit Or Receive Data, But Not Simultaneously. Ethernet Utilizes Carrier Sense Multiple Access With Collision Detect (CSMA/CD) To Control Media Access. Host Devices Monitor The Physical Link, And Will Only Transmit A Frame If The Link Is Idle.
However, If Two Devices Transmit A Frame Simultaneously, A Collision Will Occur. If A Collision Is Detected, The Hub Will Discard The Frames And Signal The Host Devices. Both Devices Will Wait A Random Amount Of Time Before Resending Their Respective Frames.
Remember, If Any Two Devices Connected To A Hub Send A Frame Simultaneously, A Collision Will Occur. Thus, All Ports On A Hub Belong To The Same Collision Domain. A Collision Domain Is Simply Defined As Any Physical Segment Where A Collision Can Occur.
Multiple Hubs That Are Uplinked Together Still All Belong To One Collision Domain. Increasing The Number Of Host Devices In A Single Collision Domain Will Increase The Number Of Collisions, Which Can Significantly Degrade Performance.
Hubs Also Belong To Only One Broadcast Domain – A Hub Will Forward Both Broadcasts And Multicasts Out Every Port But The Originating Port. A Broadcast Domain Is A Logical Segmentation Of A Network, Dictating How Far A Broadcast (Or Multicast) Frame Can Propagate.
Note:Only A Layer-3 Device, Such As A Router, Can Separate Broadcast Domains.
SUMMARY
ALSO PLZ:
CSMA/CA: - Carrier Sense Multiple Access Collision Avoidance Is A Network Access Method In Which Each Device Signals Its Intent To Transmit Before It Actually Does So. This Prevents Other Devices From Sending Information, Thus Preventing Collisions From Occurring Between Signals From Two Or More Devices. This Is The Access Method Used By Localtalk.CONCLUSION:
The Goal Of This Article Is To Give An Easy Way To Understand The “Broadcast Domains Vs Collision Domains". Hope This Article Will Help Every Beginners Who Are Going To Start Cisco Lab Practice Without Any Doubts.
Some Topics That You Might Want To Pursue On Your Own That We Did Not Cover In This Article Are Listed Here, Thank You And Best Of Luck.
This Article Written Author By: Premakumar Thevathasan. CCNA, CCNP, CCIP, MCSE, MCSA, MCSA - MSG, CIW Security Analyst, CompTIA Certified A+.
DISCLAIMER:
This Document Carries No Explicit Or Implied Warranty. Nor Is There Any Guarantee That The Information Contained In This Document Is Accurate. Every Effort Has Been Made To Make All Articles As Complete And As Accurate As Possible.
It Is Offered In The Hopes Of Helping Others, But You Use It At Your Own Risk. The Author Will Not Be Liable For Any Special, Incidental, Consequential Or Indirect Any Damages Due To Loss Of Data Or Any Other Reason That Occur As A Result Of Using This Document. But No Warranty Or Fitness Is Implied. The Information Provided Is On An "As Is" Basic. All Use Is Completely At Your Own Risk.
1 comment:
good blog.
Cloud Based Firewall
CISCO Firewall
Post a Comment