EIGRP metric calculation

The 5 Day Bootcamp workbook v4.2 task 3.16 states "Configure the EIGRP domain so that only delay is used for composite metric calculations" the solution guide shows this as

"metric weigths 0 0 0 1 0 0" 

My understanding of the values are:

K1 = Bandwidth (default 1)

K2 = Delay (default 0)

K3 = Delay Reliability (default 1)

K4 = Load (default 0)

K5 = mtu (default 0)

metric weights takes 6 arguments total (tos, k1, k2, k3, k4, k5). So to calculate on delay wouldn't we need to use only the K2 value "metric weight 0 0 1 0 0 0" to calculate on delay vice delay reliability?

 

Thanks,
Pete

 

 

 

 

Comments

  • Pete,

    The metric names aren't what they seem.  You would expect the k values to translate to bandwidth, delay, reliability, load, and MTU but they actually do not follow this same sequence.  I've looked online and found the actual representation of the k values:

    ToS is the first 0 as you know:

    k1=bandwidth

    k2=load

    k3=delay

    k4=reliability

    k5=MTU

    The answer, according to the workbook, is correct.  I struggled with this a bit myself then just realized the k values don't line up to what you memorize about the order of EIGRP metrics. 

     

     

  • I'm not so sure about the MTU there. From the Command Ref....



    If k5 equals 0, the composite EIGRP metric is computed according to the following formula:


    metric = [k1 * bandwidth + (k2 * bandwidth)/(256 - load) + k3 * delay]


    If k5 does not equal zero, an additional operation is performed:


    metric = metric * [k5/(reliability + k4)]

  • <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">






    K5 is a modifier.  It's not related to
    MTU.

     

    This tends to be a confusing issue because the 
    "default-metric" command, or "metric" on a redistribution command line puts
    CHARACTERISTICS in place which include a place for MTU, but it's not exactly
    like that when calculating the MTU.

     

    MTU is a carried concept, not one used in the metric
    itself.  The configuration guide for EIGRP should have the whole algorithm
    used for EIGRP metric calculations, this may be good to look
    at!

     

    HTH,

     




    Scott Morris, CCIE4 #4713, JNCIE-M #153, JNCIS-ER, CISSP, et al.
    CCSI/JNCI-M/JNCI-ER
    Senior CCIE Instructor

    <?xml:namespace
    prefix = st1 ns = "urn:schemas-microsoft-com:office:smarttags" />[email protected]

     

    <?xml:namespace prefix = o ns =
    "urn:schemas-microsoft-com:office:office" />
    Internetwork Expert, Inc.
    http://www.InternetworkExpert.com
    Toll
    Free: 877-224-8987
    Outside US: 775-826-4344
    Online Community:
    http://tinyurl.com/6dmnsu
    CCIE Blog:
    http://tinyurl.com/2nxxaq


    Knowledge is power.
    Power corrupts.

    Study hard and be
    Eeeeviiiil......





    From: [email protected] [mailto:[email protected]]
    On Behalf Of pesawyer
    Sent: Tuesday, December 30, 2008 3:03
    AM
    To: [email protected]
    Subject: [CCIE
    R&S] EIGRP metric calculation


    The 5 Day Bootcamp workbook v4.2 tas 3.16 states "Configure the EIGRP domain
    so that only delay is used for composite metric calculations" the solution guide
    shows this as

    "metric weigths 0 0 0 1 0 0" 

    My understanding of the values are:

    K1 = Bandwidth (default 1)

    K2 = Delay (default 0)

    K3 = Delay Reliability (default 1)

    K4 = Load (default 0)

    K5 = mtu (default 0)

    metric weights takes 6 arguments total (tos, k1, k2, k3, k4, k5). So to
    calculate on delay wouldn't we need to use only the K2 value "metric weight 0 0
    1 0 0 0" to calculate on delay vice delay reliability?

     

    Thanks,
    Pete

     

     

     

     




    Internetwork
    Expert - The Industry Leader in CCIE
    Preparation
    http://www.internetworkexpert.com

    Subscription information
    may be found
    at:
    http://www.ieoc.com/forums/ForumSubscriptions.aspx
  • I took Mock Lab 5 on Saturday. One of the tasks asked for a certain combination of metrics to be considered throughout the EIGRP domain. By looking at the formula in the Configuration Guide I was able to correctly identify the k-values to enable the required metrics.

    This is one time where using the documentation is better than relying on memory.



  •  

    EIGRP Metric = 256*((K1*Bw) + (K2*Bw)/(256-Load) + (K3*Delay)*(K5/(Reliability + K4)))

    So, I don't see how someone can identify the values of metric weights tos k1 k2 k3 k4 k5 


    from that formula. Cisco's formula in the documentation doesn't help me configure the metric weights, so if someone knows where to find that in the documentation that's great to know. Otherwise, seems I'm stuck memorizing 10^7/min BW + delay in 10's of microseconds * 256


    On Tue, Dec 30, 2008 at 3:28 PM, DarrellEscola <[email protected]> wrote:

    I took Mock Lab 5 on Saturday. One of the tasks asked for a certain combination of metrics to be considered throughout the EIGRP domain. By looking at the formula in the Configuration Guide I was able to correctly identify the k-values to enable the required metrics.

    This is one time where using the documentation is better than relying on memory.





    Internetwork Expert - The Industry Leader in CCIE Preparation
    http://www.internetworkexpert.com

    Subscription information may be found at:
    http://www.ieoc.com/forums/ForumSubscriptions.aspx


  • Ok, thanks. It's a little more clear to me now.

  • I think in this case, the Command Ref is a better source than the Config Guide. The Command Ref lays the formula out nicely and the variables are explained clearly....

    http://www.cisco.com/en/US/docs/ios/iproute/command/reference/irp_eig2.html#wp1011716

     

  • On 30/12/2008, at 7:03 PM, pesawyer wrote:

    > The 5 Day Bootcamp workbook v4.2 tas 3.16 states "Configure the
    > EIGRP domain so that only delay is used for composite metric
    > calculations" the solution guide shows this as
    >
    > "metric weigths 0 0 0 1 0 0"
    >
    > My understanding of the values are:
    >
    > K1 = Bandwidth (default 1)
    >
    > K2 = Delay (default 0)
    >
    > K3 = Delay Reliability (default 1)
    >
    > K4 = Load (default 0)
    >
    > K5 = mtu (default 0)
    >
    > metric weights takes 6 arguments total (tos, k1, k2, k3, k4, k5). So
    > to calculate on delay wouldn't we need to use only the K2 value
    > "metric weight 0 0 1 0 0 0" to calculate on delay vice delay
    > reliability?
    >

    Hi Peter,

    K1 and K2 are for Bandwidth. K3 is for Delay. Just check the formula
    to get a better understanding.

    Thx
    David Sudjiman
    www.davidsudjiman.info
  • You are confusing the metrics used in the "default-metric" command or
    "redistribute" command with the K values. They are different.

    If you look at the algorithm used for metrics, you'll find that:

    K1 - bandwidth
    K2 - load
    K3 - delay
    K4 - reliability
    K5 - just a modifier

    Tos is always 0 in the "metric weights" command.

    HTH,

    Scott




    ----- Original Message -----
    From: "David Sudjiman"
    Sent: Sun, February 22, 2009 21:43
    Subject:Re: [CCIE R&S] EIGRP metric calculation


    On 30/12/2008, at 7:03 PM, pesawyer wrote: > The 5 Day Bootcamp workbook
    v4.2 tas
    3.16 states "Configure the > EIGRP domain so that only delay is used for
    composite
    metric > calculations" the solution guide shows this as > > "metric
    weigths 0 0 0 1
    0 0" > > My understanding of the values are: > > K1 = Bandwidth (default
    1) > > K2 =
    Delay (default 0) > > K3 = Delay Reliability (default 1) > > K4 = Load
    (default 0) >
    > K5 = mtu (default 0) > > metric weights takes 6 arguments total (tos,
    k1, k2, k3,
    k4, k5). So > to calculate on delay wouldn't we need to use only the K2
    value >
    "metric weight 0 0 1 0 0 0" to calculate on delay vice delay >
    reliability? > Hi
    Peter, K1 and K2 are for Bandwidth. K3 is for Delay. Just check the
    formula to get a
    better understanding. Thx David Sudjiman www.davidsudjiman.info

    --
    View this message online at: http://ieoc.com/forums/p/4483/17801.aspx#17801
    --
    Internetwork Expert - The Industry Leader in CCIE Preparation

    http://www.internetworkexpert.com



    Subscription information may be found at:

    http://www.ieoc.com/forums/ForumSubscriptions.aspx


    ----- End of original message --
Sign In or Register to comment.