EIGRP OVERVIEW
Unlike IGRP, Which Is A Classful Routing Protocol, EIGRP Supports Classless Interdomain Routing Novell Routing Information Protocol (RIP) And Appletalk Routing Table Maintenance Protocol (RTMP), Serving Both IPX And Appletalk Networks With Powerful Efficiency.
EIGRP Is Often Described As A Hybrid Routing Protocol, Offering The Best Of Distance Vector And Link-State Algorithms.
EIGRP Is An Advanced Routing Protocol That Relies On Features Commonly Associated With Link-State Protocols. Some Of The Best Features Of OSPF, Such As Partial Updates And Neighbour Discovery Are Similarly Put To Use By EIGRP. However, EIGRP Is Easier To Configure Than OSPF.
EIGRP Is An Ideal Choice For Large, Multi-Protocol Networks Built Primarily On Cisco Routers.
EIGRP EMPLOYS FOUR KEY TECHNOLOGIES THAT COMBINE TO DIFFERENTIATE IT FROM OTHER ROUTING TECHNOLOGIES: ✓ 1. Neighbor Discovery/Recovery,
✓ 2. Reliable Transport Protocol (RTP),
✓ 3. DUAL Finite-State Machine,
✓ 4. Protocol-Dependent Modules.
The Neighbor Discovery/Recovery Mechanism Enables Routers To Dynamically Learn About Other Routers On Their Directly Attached Networks. Routers Also Must Discover When Their Neighbors Become Unreachable Or Inoperative. This Process Is Achieved With Low Overhead By Periodically Sending Small Hello Packets. As Long As A Router Receives Hello Packets From A Neighboring Router, It Assumes That The Neighbor Is Functioning, And The Two Can Exchange Routing Information.
Reliable Transport Protocol (RTP) Is Responsible For Guaranteed, Ordered Delivery Of EIGRP Packets To All Neighbors. It Supports Intermixed Transmission Of Multicast Or Unicast Packets. For Efficiency, Only Certain EIGRP Packets Are Transmitted Reliably. On A Multiaccess Network That Has Multicast Capabilities, Such As Ethernet, It Is Not Necessary To Send Hello Packets Reliably To All Neighbors Individually. For That Reason, EIGRP Sends A Single Multicast Hello Packet Containing An Indicator That Informs The Receivers That The Packet Need Not Be Acknowledged. Other Types Of Packets, Such As Updates, Indicate In The Packet That Acknowledgment Is Required. RTP Contains A Provision For Sending Multicast Packets Quickly When Unacknowledged Packets Are Pending, Which Helps Ensure That Convergence Time Remains Low In The Presence Of Varying Speed Links.
The DUAL Finite-State Machine Embodies The Decision Process For All Route Computations By Tracking All Routes Advertised By All Neighbors. DUAL Uses Distance Information To Select Efficient, Loop-Free Paths And Selects Routes For Insertion In A Routing Table Based On Feasible Successors. A Feasible Successor Is A Neighboring Router Used For Packet Forwarding That Is A Least-Cost Path To A Destination That Is Guaranteed Not To Be Part Of A Routing Loop. When A Neighbor Changes A Metric, Or When A Topology Change Occurs, DUAL Tests For Feasible Successors. If One Is Found, DUAL Uses It To Avoid Recomputing The Route Unnecessarily. When No Feasible Successors Exist But Neighbors Still Advertise The Destination, A Recomputation (Also Known As A Diffusing Computation) Must Occur To Determine A New Successor. Although Recomputation Is Not Processor-Intensive, It Does Affect Convergence Time, So It Is Advantageous To Avoid Unnecessary Recomputations.
Protocol-Dependent Modules Are Responsible For Network Layer Protocol-Specific Requirements. The IP-EIGRP Module, For Example, Is Responsible For Sending And Receiving EIGRP Packets That Are Encapsulated In IP. Likewise, IP-EIGRP Is Also Responsible For Parsing EIGRP Packets And Informing DUAL Of The New Information That Has Been Received. IP-EIGRP Asks DUAL To Make Routing Decisions, The Results Of Which Are Stored In The IP Routing Table. IP-EIGRP Is Responsible For Redistributing Routes Learned By Other IP Routing Protocols.
EIGRP Supports Both Internal And External Routes: Routes That Are Internal To An AS Are Completely Contained Within That AS. External Routes Are Those That Are Learned From Neighbors That Lie Outside The AS. External Routes Are Tagged With Information That Identifies Their Origin. This Enables A Network Administrator To Develop Customized Interdomain Routing Policies.
COMPARING EIGRP WITH IGRP: Cisco Released EIGRP In 1994 As A Scalable, Improved Version Of Its Proprietary Distance Vector Routing Protocol, IGRP. The Same Distance Vector Technology Found In IGRP Is Used In EIGRP, And The Underlying Distance Information Remains The Same.
EIGRP Improves The Convergence Properties And The Operating Efficiency Significantly Over IGRP. This Allows For An Improved Architecture While Retaining The Existing Investment In IGRP.
IGRP And EIGRP Are Compatible With Each Other. This Compatibility Provides Seamless Interoperability With IGRP Routers. This Is Important So Users Can Take Advantage Of The Benefits Of Both Protocols. EIGRP Offers Multiprotocol Support, But IGRP Does Not.
EIGRP And IGRP Use Different Metric Calculations. EIGRP Scales The Metric Of IGRP By A Factor Of 256. That Is Because EIGRP Uses A Metric That Is 32 Bits Long, And IGRP Uses A 24-Bit Metric. By Multiplying Or Dividing By 256, EIGRP Can Easily Exchange Information With IGRP.
IGRP Has A Maximum Hop Count Of 255. EIGRP Has A Maximum Hop Count Limit Of 224. This Is More Than Adequate To Support The Largest, Properly Designed Internetworks.
Enabling Dissimilar Routing Protocols Such As OSPF And RIP To Share Information Requires Advanced Configuration. Redistribution, The Sharing Of Routes, Is Automatic Between IGRP And EIGRP As Long As Both Processes Use The Same Autonomous System (AS) Number.
EIGRP ROUTING CONCEPTS: ✓ 1. Neighbor Tables,
✓ 2. Topology Tables,
✓ 3. Route States,
✓ 4. Route Tagging.
NEIGHBOR TABLES: When A Router Discovers A New Neighbor, It Records The Neighbor's Address And Interface As An Entry In The Neighbor Table. One Neighbor Table Exists For Each Protocol-Dependent Module. When A Neighbor Sends A Hello Packet, It Advertises A Hold Time, Which Is The Amount Of Time That A Router Treats A Neighbor As Reachable And Operational. If A Hello Packet Is Not Received Within The Hold Time, The Hold Time Expires And DUAL Is Informed Of The Topology Change.
The Neighbor-Table Entry Also Includes Information Required By RTP. Sequence Numbers Are Employed To Match Acknowledgments With Data Packets, And The Last Sequence Number Received From The Neighbor Is Recorded So That Out-Of-Order Packets Can Be Detected. A Transmission List Is Used To Queue Packets For Possible Retransmission On A Per-Neighbor Basis. Round-Trip Timers Are Kept In The Neighbor-Table Entry To Estimate An Optimal Retransmission Interval.
TOPOLOGY TABLES: The Topology Table Contains All Destinations Advertised By Neighboring Routers. The Protocol-Dependent Modules Populate The Table, And The Table Is Acted On By The DUAL Finite-State Machine. Each Entry In The Topology Table Includes The Destination Address And A List Of Neighbors That Have Advertised The Destination. For Each Neighbor, The Entry Records The Advertised Metric, Which The Neighbor Stores In Its Routing Table. An Important Rule That Distance Vector Protocols Must Follow Is That If The Neighbor Advertises This Destination, It Must Use The Route To Forward Packets.
The Metric That The Router Uses To Reach The Destination Is Also Associated With The Destination. The Metric That The Router Uses In The Routing Table, And To Advertise To Other Routers, Is The Sum Of The Best-Advertised Metric From All Neighbors And The Link Cost To The Best Neighbor.
ROUTE STATES : A Topology-Table Entry For A Destination Can Exist In One Of Two States: Active Or Passive. A Destination Is In The Passive State When The Router Is Not Performing A Recomputation; It Is In The Active State When The Router Is Performing A Recomputation. If Feasible Successors Are Always Available, A Destination Never Has To Go Into The Active State, Thereby Avoiding A Recomputation.
A Recomputation Occurs When A Destination Has No Feasible Successors. The Router Initiates The Recomputation By Sending A Query Packet To Each Of Its Neighboring Routers. The Neighboring Router Can Send A Reply Packet, Indicating That It Has A Feasible Successor For The Destination, Or It Can Send A Query Packet, Indicating That It Is Participating In The Recomputation. While A Destination Is In The Active State, A Router Cannot Change The Destination's Routing-Table Information. After The Router Has Received A Reply From Each Neighboring Router, The Topology-Table Entry For The Destination Returns To The Passive State, And The Router Can Select A Successor.
ROUTE TAGGING: EIGRP Supports Internal And External Routes. Internal Routes Originate Within An EIGRP AS. Therefore, A Directly Attached Network That Is Configured To Run EIGRP Is Considered An Internal Route And Is Propagated With This Information Throughout The EIGRP AS. External Routes Are Learned By Another Routing Protocol Or Reside In The Routing Table As Static Routes. These Routes Are Tagged Individually With The Identity Of Their Origin.
EIGRP DUAL: The Lowest-Cost Route Is Calculated By Adding The Cost Between The Next-Hop Router And The Destination (Advertised Distance [AD]), And The Cost Between The Local Router And The Next Hop. This Sum Is Referred To As The Feasible Distance (FD).
A Successor Is A Neighboring Router That The Local Router Has Selected To Forward Packets To The Destination. Multiple Successors Can Exist If They Have Equal-Cost Paths.
The Next-Hop Router For A Backup Path Is Called The Feasible Successor. To Qualify As A Feasible Successor, A Next-Hop Router Must Have An AD Less Than The FD Of The Current Successor Route. More Than One Feasible Successor Can Exist.
The Feasible Successor Means That A New Path Can Be Selected Without Recalculation And Is A Major Advantage In EIGRP For Convergence.
Remember, EIGRP Acts Classful By Default And Automatically Summarizes On Major Network Boundaries. You Typically Want To Disable This Feature With The No Auto-Summary Router Configuration Command As Mentioned Above.
EXTERNAL ROUTES ARE TAGGED WITH THE FOLLOWING INFORMATION: ✓ Router ID Of The EIGRP Router That Redistributed The Route
✓ AS Number Of The Destination
✓ Configurable Administrator Tag
✓ ID Of The External Protocol
✓ Metric From The External Protocol
✓ Bit Flags For Default Routing
Route Tagging Allows The Network Administrator To Customize Routing And Maintain Flexible Policy Controls. Route Tagging Is Particularly Useful In Transit Ass, Where EIGRP Typically Interacts With An Interdomain Routing Protocol That Implements More Global Policies, Resulting In A Very Scalable, Policy-Based Routing.
EIGRP SHORT NOTES
◙ Advanced Distance Vector
ROUTE SUMMARIZATION: EIGRP Performs Auto-Summarization By Default. You Can Enable Manual Summarization. The Following In Mind About Manual Summarization:
✓ Summarization Is Configurable On A Per-Interface Basis In Any Router Within The Network
✓ When Summarization Is Configured On An Interfaces, The Router Immediately Creates A Route Pointing To Null0. This Is A Loop-Prevention Mechanism
✓ When The Last Specific Route Of The Summary Goes Away, The Summary Is Deleted
✓ The Minimum Metric Of The Specific Routes Is Used As The Metric Of The Summary Route.
Use The IP Summary-Address EIGRP Interface Command To Manually Create A Summary Route At An Arbitrary Network Boundary Within An Eigrp Domain.
◙ Automatic Summarization At Classful Boundary (Can Be Disabled/Turned Off)
✓ Supports VLSM/CIDR
✓ Manually Summarized Routes Have Ad Of 5, Point To Null0
✓ More Specific Routes Within Summarized Range Must Exist In Routing Table, Or Summarized Route Disappears
◙ Multicast Address 224.0.0.10
✓ Unicast And Multicast Are Used For Updates
◙ IP/IPX/APPLETALK Routed Protocol Support
◙ No Special Configuration Required For Various Layer 2 Technologies
UNEQUAL-COST LOAD BALANCING: The Degree To Which EIGRP Performs Load Balancing Is Controlled With The Variance Command.
You Set The Variance To A Number From 1 To 128. The Default Is 1, Which Indicates Equal-Cost Load Balancing. The Multiplier Defines The Range Of Metric Values That Are Accepted For Load Balancing By The EIGRP Process.
◙ Unequal Cost Load Balancing
SUCCESSOR AND FEASIBLE SUCCESSOR: ◙ Successor - Best Path To A Destination. Placed In The Routing Table.
Think Of The Successor As The Active, Or Primary, Route To A Destination For EIGRP. The Successor Is Actually The Neighbor Router That Has The Least-Cost Path To A Destination Network (A.K.A. Has The Lowest Feasible Distance). Successor Routes Are Added Directly To The Routing Table. You Should Also Know That Multiple Successors Can Exists If They Have Identical Feasible Distance Values.
◙ Feasible Sucessor - Second Best Path To A Destination. Possible Back-Up/Secondary Paths To Get To The Destination. Pleased In The Topology Table .
This Is More Like The Backup Route EIGRP Chooses To A Destination Network. The Feasible Successor Feature Is What Makes EIGRP Convergence So Unique And So Fast. It Always Tries To Find A Backup Route. In The Event That The Successor Fails, It Can Immediately Switch Over To The Feasible Successor (Backup) Route With Very Little Delay. To Qualify As A Feasible Successor, The AD Must Be Less Than The Successor’s FD. This Helps Ensure A Loop-Free Layer 3 Path.
✓ Feasible Distance - Cost From Local Router To Final Destination. This Is The Cost Of The Local Routers Best Path To The Destination. This Cost Is Associated With The Successor (Primary) Routes To Each Destination Network.
✓ Reported Distance – This Is The Feasible Distance Reported From Neighboring Routers. This Figure Is Used To Decide If Another Path Can Be Considered A Feasible Successor (Back-Up) Route.
✓ Feasibility Condition – In Order To Be A Feasible Successor And Get Placed In The Topology Table, The Reported Distance Of A Route Must Be LOWER Than The Feasible Distance Of The Successor Route.
✓ Advertised Distance - Cost From Next Hop To Final Destination
For Feasible Successor To Be Used, AD Must Be Less Than The FD Through Successor
EIGRP PACKET TYPES : RTP: Is Responsible For Providing Guaranteed Delivery Of EIGRP Packets Between Neighboring Routers. However, Not All Of The EIGRP Packets That Neighbors Exchange Must Be Sent Reliably. Some Packets, Such As Hello Packets, Can Be Sent Unreliably. More Importantly, They Can Be Multicast Rather Than Having Separate Datagrams With Essentially The Same Payload Being Discretely Addressed And Sent To Individual Routers. This Helps An EIGRP Network Converge Quickly, Even When Its Links Are Of Varying Speeds.
EIGRP Uses The Following Packet Types: Hello And Acknowledgment, Update, And Query And Reply.
Hello Packets Are Multicast For Neighbor Discovery/Recovery And Do Not Require Acknowledgment. An Acknowledgment Packet Is A Hello Packet That Has No Data. Acknowledgment Packets Contain A Nonzero Acknowledgment Number And Always Are Sent By Using A Unicast Address.
Update Packets Are Used To Convey Reachability Of Destinations. When A New Neighbor Is Discovered, Unicast Update Packets Are Sent So That The Neighbor Can Build Up Its Topology Table. In Other Cases, Such As A Link-Cost Change, Updates Are Multicast. Updates Always Are Transmitted Reliably.
Query And Reply Packets Are Sent When A Destination Has No Feasible Successors. Query Packets Are Always Multicast. Reply Packets Are Sent In Response To Query Packets To Instruct The Originator Not To Recompute The Route Because Feasible Successors Exist. Reply Packets Are Unicast To The Originator Of The Query. Both Query And Reply Packets Are Transmitted Reliably.
◙ HELLO PACKETS ARE SENT EVERY 5 SECONDS ON LINKS GREATER THAN T1:
✓ Sent Every 60 Seconds For T1 And Slower
✓ Hold Time Interval Defaults To 3 Times The Hello Interval
✓ Changing Default Hello Interval Does Not Automatically Update The Hold Time
✓ IP HELLO-INTERVAL EIGRP {As} {Seconds} Interface Command
✓ IP HOLD-TIME EIGRP {As} {Seconds} Interface Command
◙ Un-Acknowledged Multicast Updates Are Unicast To The Host That Did Not Ack. This Avoids Hold Ups With Further Updates To The Rest Of The Network
METRIC CALCULATION:
✓ Bandwidth - Defined As 107 Divided By The Speed Of The Slowest Link In The Path, In Kbps
✓ Load - 8-Bit Value, Not Considered By Default
✓ Reliability - 8-Bit Value, Not Considered By Default
✓ Delay - Constant Value Associated With Interface Type; EIGRP Uses The Sum Of All Delays In The Path
K VALUES: K Values Are Constants Used To Distribute Weight To Different Path Aspects.
K Defaults: K1 = 1
K2 = 0
K3 = 1
K4 = 0
K5 = 0
K Values Can Be Manipulated By An Administrator, But Routers Must Have Matching K Values To Become Neighbors. Manipulation Of The Default K Values Is Generally Not Recommended, As It May Lead To Unpredictable Metric Calculations.
◙ EIGRP Metric Is Based On Load, Bandwidth, Delay, And Reliability.
✓ Cisco Recommends Leaving K Values At Default
CONFIGURATION OF EIGRP: ✓ Router EIGRP {As}
✓ Network {Address | Wildcard Mask} (Wildcard Is Optional)
✓ No Auto-Summary (Turns Off Summarization At Classful Boundary)
✓ Redistribute Static (Redistributes Any Static Routes Into The Protocol)
✓ Variance {#} (Modifies Which Routes Will Be Considered For Unequal Cost Load Balancing)
✓ Max-Paths {#} (Number Of Paths To Be Used For Load Balancing. Default Is 4, Max Is 16)
✓ IP Summary-Address EIGRP {As} {Address | Mask} (Interface Configuration Command To Summarize Routes At A Non Classful Boundary.)
✓ EIGRP Stub Receive-Only ( This Creates A Stub In Eigrp. The “Receive-Only Option” Tells The Stub Router To Not Send Any Routes)
CONFIGURATION VERIFICATION: It Is So Important To Verify Your Configuration, A Command That Deserves Some Elaboration Is The Show IP EIGRP Topology. The Codes In The Output Are As Follows:
✓ Active - This Network Is Available, And Installation Can Occur In The Routing Table
✓ Passive - This Network Is Currently Unavailable
✓ Update (U) - Applies If A Network Is Being Updated (Placed In An Update Packet); This Code Also Applied If The Router Is Waiting For An Acknowledgment For This Update Packet.
✓ Query (Q) - Applied If An Outstanding Query Packet Exists For This Network Other Than Being In The Active State; Also Applies If The Router Is Waiting For An Acknowledgment For A Query Packet.
✓ Reply (R) - Applies If The Router Is Generating A Reply For This Network Or Is Waiting For An Acknowledgment For The Reply Packet.
✓ Stuck In Active (SIA) Status - Signifies An EIGRP Convergence Problem For The Network With Which It Is Associated.
EIGRP AUTHENTICATION: ✓ EIGRP Supports CLEARTEXT AND MD5 Authentication. It Looks Like We’re Only Concerned With MD5 For The Exams (For Obvious Security Reasons)
EIGRP MD5 AUTHENTICATION: EIGRP MD5 Authentication Ensures That Routers Accept EIGRP Packets Only From Trusted Sources. After The MD5 Authentication Is Configured On An Interface, Every EIGRP Packet Sent By A Router Over That Interface Is Signed With An MD5 Fingerprint. Every EIGRP Packet Received Over An Interface With MD5 Authentication Configured Is Checked To Verify That The MD5 Fingerprint In The Packet Matches The Expected Value, Making It Impossible For The Intruder To Insert Untrusted Routers In The Network Or Send Bogus Packets To The Routers.
MD5 Is An Algorithm Described In RFC 1321 That Takes A Message (EIGRP Packet) And Generates 128 Bits Of Hash Value (Called Message Digest Or Fingerprint) With Several Properties That Make MD5 Usable In Very Secure Signature Implementations
✓ IP AUTHENTICATION MODE EIGRP {As} MD5 (Interface Config Mode)
✓ IP AUTHENTICATION KEY-CHAIN EIGRP {AS} {NAME OF KEYCHAIN}
✓ KEY CHAIN {NAME OF KEYCHAIN} (Global Config Mode)
➤ KEY {KEY-ID} (This Can Be Between 0-2147483647)
➤ KEY-STRING {KEY}
◙ As Of IOS 12.3, EIGRP Sends A Graceful Goodbye Message When Bringing The Process Down. Goodbye Messages Are Sent Inside Of Hello Packets
ROUTE QUERIES: When A Router Loses Its Successor And Has No Feasible Successors, It Will Query All Remaining Neighbors For A New Route. Queries Are Recursive And Will Be Forwarded To Other Neighbors Until Either A Route Is Found, Or A Summarization Boundary Is Reached.
An EIGRP Process Is Considered "Stuck In Active (SIA)" And Must Be Reset When One Or More Queries To A Neighbor Do Not Return A Route Before The Active Timer Expires (Typically 3 Minutes).
HELPFUL COMMANDS: Show IP EIGRP Neighbors
Show IP Route
Show IP Route EIGRP
Show IP Protocols – > Shows Active Routing Protocol Info (Displays K Values)
Show IP EIGRP Interfaces
Show IP EIGRP Toplogy – > Successor/Feasible Successor
Show IP EIGRP Traffic
Debug EIGRP Packets
KEY TECHNOLOGIES: ✓ Dual Finite State
✓ RTP
✓ Neighbor Discovery/Recovery
✓ Protocol Dependant Modules (IP, IPX, APPLETALK)
NETWORK PROBLEMS COMMONLY RESULT FROM THE FOLLOWING: ✓ Mistyped Commands
✓ Incorrectly Constructed Or Incorrectly Placed Access Lists
✓ Misconfigured Routers, Switches, Or Other Network Devices
✓ Bad Physical Connections
TROUBLESHOOTING OF EIGRP INCLUDING: ✓ Troubleshoot A RIP Routing Process Using Show And Debug Commands
✓ Troubleshoot An IGRP Routing Process Using Show And Debug Commands
✓ Troubleshoot An EIGRP Routing Process Using Show And Debug Commands
✓ Troubleshoot An OSPF Routing Process Using Show And Debug Commands
EIGRP STUB ROUTING: Often Used In A Hub-And-Spoke Topology. Only Routes You Specify Are Propagated From The Stub Router. The Stub Router Responds To All Queries With The Message "Inaccessible". A Router That Is Configured As A Stub Sends A Special Peer Information Packet To All Neighboring Routers To Report Its Status As A Stub Router. Non-Stub Routers Do Not Query Stub Routers. The Stub Routing Feature By Itself Does Not Prevent Routes From Being Advertised To The Stub Router. You Must Configure The Summarization Or Default Route Behavior. To Configure The Stub Router, Use The Following Router Configuration Command: EIGRP Stub [Receive-Only | Connected | Static | Summary]
The Optional Keywords With This Command Control Which Routes The Router Advertises To Its Non-Stub Peers. Receive-Only Is Very Dangerous, If You Use It, Your Router Will Lose Its Adjacency With The Neighboring Router Causing The Link To Disconnect.
CONCLUSION:
The Goal Of This Article Is To Give An Easy Way To Understand The “EIGRP Quick Reference” And Also We Hope This Guide Will Help Every Beginner 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!Hands - On Experience Is An Invaluable Part Of Preparing For The Lab Exam And Never Pass Up An Opportunity To Configure Or Troubleshoot A Router ( If You Have Access To Lab Facilities, Take Full Advantage Of Them) There Is No Replacement For The Experience You Can Gain From Working In A Lab, Where You Can Configure Whatever You Want To Configure And Introduce Whatever Problems You Want To Introduce, Without Risk Of Disrupting A Production Network. Thank You And Best Of Luck
This Article Written Author By: Premakumar Thevathasan - CCNA, CCNP, MCSE, MCSA, MCSA - MSG, CIW Security Analyst, CompTIA Certified A+ And Etc.
WARNING AND 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, But No Warranty Or Fitness Is Implied.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.
This Guide Provides Technical Guidance Intended To Help Network Students And Network Administrators Officers Improve The Security Of Their Networks.
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