CISCO - EIGRP QUICK REFERENCE:

► CISCO PROPRIETARY PROTOCOL

► ADVANCED DISTANCE VECTOR

► 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

► SUCCESSOR - BEST PATH TO A DESTINATION

► FEASIBLE SUCESSOR - SECOND BEST PATH TO A DESTINATION

    

ADVERTISED DISTANCE - COST FROM NEXT HOP TO FINAL DESTINATION
    

FEASIBLE DISTANCE - COST FROM LOCAL ROUTER TO FINAL DESTINATION
    

FOR FEASIBLE SUCCESSOR TO BE USED, AD MUST BE LESS THAN THE FD THROUGH SUCCESSOR

► 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

► 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)

► EIGRP AUTHENTICATION

    

EIGRP SUPPORTS CLEARTEXT AND MD5 AUTHENTICATION. IT LOOKS LIKE WE’RE ONLY CONCERNED WITH MD5 FOR THE EXAMS (FOR OBVIOUS SECURITY REASONS)

    

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

► 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)

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CONCLUSION:

The Goal Of This Article Is To Give An Easy Way To Understand The “CISCO - EIGRP QUICK REFERENCE". 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+.

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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.