Wrong With This Lecture

Hi Everyone Into IEOC

https://streaming.ine.com/c/ine-ccna-guide-to-eigrp

4-Metrics & Tables

here`s another wrong

image


K5 into Eigrp Metric NOT Reliability, it`s MTU

and it`s not used into calculation value

k5 and hop count are values not used into eigrp metric calculation

Comments

  • MartinlMartinl ✭✭✭

    [Y]

  • Hello and Good Morning Mohamed!  Yes, that is definitely a typo and my guess is that I cut and pasted the K4 value from above and forgot to change it.  I have updated the deck and passed it on to the production team at INE and the slides should be updated shortly.  Thank you!

    Cheers,

    Travis

  • MartinlMartinl ✭✭✭

    [Y]

  • Hi Everyone Into IEOC

    https://streaming.ine.com/c/ine-ccna-guide-to-eigrp

    4-Metrics & Tables

    here`s another wrong

    image


    K5 into Eigrp Metric NOT Reliability, it`s MTU

    and it`s not used into calculation value

    k5 and hop count are values not used into eigrp metric calculation

     

    K5 is definitely NOT MTU. Actually Travis is right and it is a reliability modifier. It's also contradictory to say that  K5 is MTU while at the same time saying MTU is not used in the EIGRP metric calculation when the K5 value is very clearly part of the metric. Here are two sources to clarify things.

    From Scott Morris at https://learningnetwork.cisco.com/thread/9022

    MTU is not a K-value.  But people often confuse the K-values with
    metric values.  There are two places in the CLI where we can enter
    things.

     

    In the
    redistribute command or default-metric command (yes, I know, two
    commands, but only one "place" for redistribution!) we enter five VALUES
    of a metric.  Bandwidth, delay, load, reliability and MTU.  That sets a
    baseline metric and describes the weighting of the route.

     

    Then
    we have the routing algorithm itself, which is fairly long and
    convoluted...   But this is where the K-values actually come into play. 
    These are MODIFIERS of metric information (NOT raw metric
    information).  By default, these values are 1's or 0's which essentially
    just turns ON or OFF parts of the overall mathematical equation.

     

    But
    looking at the algorithm (found in the EIGRP Configuration Guide under
    the documentation on CCO), you'll find NO mention whatsoever about MTU.

     

    K1 = Bandwidth modifier

    K2 = Load modifier

    K3 = Delay modifier

    K4 = Reliability modifier

    K5 = Additional Reliability modifier

     

    Now,
    MTU is indeed used though.  You have the concept of "minimum MTU along
    path" that is carried with routing information.  Kind of a pre-emptive
    TCP MSS path discovery measurement. 

     

    But
    many documents confuse the two and assume they are directly related.  I
    have LOTS of CCIE candidates that I train who had always been under
    that impression.  So I'm glad to hear that an ICND book is starting to
    right the wrongs of the world. 

     

    And also from Diane Teare in her Implementing Cisco IP Routing (ROUTE) book.

    You might find it in many books or online articles
    that maximum transmission unit (MTU) is also used in EIGRP metric
    calculations. Although it is true that MTU value is exchanged in the
    routing updates together with other metric components, it is never used
    for the metric calculation. It is only used as a tie-breaker, when the
    router needs to ignore some equal-cost paths to the same destination,
    because of too many equal-cost paths. In such cases, the route with the
    highest minimum MTU is preferred.

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