Skip navigation
Cisco Learning Home > CCIE Routing and Switching Study Group > Discussions
2062 Views 7 Replies Latest reply: Mar 11, 2012 12:27 PM by Nersas Marin RSS

Currently Being Moderated

EIGRP - Load Distribution

Mar 10, 2012 2:14 AM

Nersas Marin 61 posts since
Oct 24, 2009

Hello!!! I'm working load balancing traffic with EIGRP between fastethernet and serial interfaces to a destination point. One time that I get the condition and configure variance to 100 (for example) I get traffic sharing to the destinion.
The problem is that I never get match exact metric (for example 3:1). The closest solution is the one that I attach in the picture:

 

Ethernet Traffic share count it 41

Serial Traffic share count it 120

 

Is it a valid solucion in the CCIE lab?? How much allowance do we have to match the correct answer?? I mean, 44:124 should be a valid solution???

 

I always try to apply the formula but I never get the exact right number:

 

3*Metric = Metric

3 * (10^7/BW + DL1) = (10^7/BW + DL2)

3 * (10^7/BW + xxx(Whaterver you define)) = (10^7/BW + DL2)

DL2 = answer

Attachments:
  • lp4nb 520 posts since
    Jun 27, 2009
    Currently Being Moderated
    1. Mar 10, 2012 3:45 AM (in response to Nersas Marin)
    Re: EIGRP - Load Distribution

    What actually is being asked to configure in your lab?

    If they say you have to match the traffic share count as told, then you have to configure in a way to match as it is.

    If you could paste some scenario/configs, that may be helpful.

     

     

    Regards.

  • lp4nb 520 posts since
    Jun 27, 2009
    Currently Being Moderated
    3. Mar 10, 2012 4:37 AM (in response to Nersas Marin)
    Re: EIGRP - Load Distribution

    as the minimum BW is same, lets change the weights for removing the unnecessary complex calculations.

     

    Now, the default delay at R1 for network 10.1.23.0 is 40,000 U sec from R1-R3-, and 21000 Usec from R1 - R2-

     

    metric from R3 = 3* metric from R2

    256.(40000 + x) = 3.*256*21000

    40,000 + x = 63000

    x= 63000- 40000

    x= 23000

     

     

    so on R1 on interface s0/0

     

    interface s0/0

    delay 4300

    exit

     

    R1(config)#do sh ip route 10.1.23.0

    Routing entry for 10.1.23.0/24

      Known via "eigrp 21", distance 90, metric 537600, type internal

      Redistributing via eigrp 21

      Last update from 10.1.13.3 on Serial0/0, 00:00:09 ago

      Routing Descriptor Blocks:

        10.1.13.3, from 10.1.13.3, 00:00:09 ago, via Serial0/0

          Route metric is 1612800, traffic share count is 1

          Total delay is 63000 microseconds, minimum bandwidth is 1544 Kbit

          Reliability 255/255, minimum MTU 1500 bytes

          Loading 1/255, Hops 1

      * 10.1.12.2, from 10.1.12.2, 00:00:09 ago, via FastEthernet0/0

          Route metric is 537600, traffic share count is 3

          Total delay is 21000 microseconds, minimum bandwidth is 1544 Kbit

          Reliability 255/255, minimum MTU 1500 bytes

          Loading 1/255, Hops 1

     

    Regards

  • cadetalain 2,642 posts since
    Sep 18, 2008
    Currently Being Moderated
    5. Mar 10, 2012 5:52 AM (in response to Nersas Marin)
    Re: EIGRP - Load Distribution

    Hi Nersas,

     

    just my two cents: the values  lp4nb used are the delays in tens of microseconds and of course you can let  go of 256 as it is amultiplier on both sides of the equation.

     

    Regards.

     

    Alain

  • lp4nb 520 posts since
    Jun 27, 2009
    Currently Being Moderated
    6. Mar 10, 2012 6:44 AM (in response to Nersas Marin)
    Re: EIGRP - Load Distribution

    When you apply the formula, do you really need to " * 256" ?? If you do it in both sides, isn't it the same???

    Choice is yours.

     

     

    In your simulation, you define 40000 for serial connection R1-R3. Is it comming from BW^7 / BW-link Kbps + Delay R1-R3 ???
    In your simulation, you define 21000 for serial connection R1-R2. Is it comming from BW^7 / BW-link Kbps + Delay R1-R2???

     

    yes, the cumulative delay is the delay of serial on R3 s0/1, + delay on serial on R1 s0/0

     

    same for the path from R2 to R1.

     

    If you expand, a factor of 256*(min BW) is added to both sides of the equation.

    So, it infact is same thing, as its equal both sides.

     

    Regards

     

    P.S I didn't know if it was for R4, if its for R4 you can do the same for 4.4.4.4.

    the catch would be, delay factor for serial s0/0 on R2.

     

    metric from R3 = 3* metric from R2

     

    (20000 +40000 + x) = 3*(21000 +20000)  [ no need to use, 256, or BW stuff, as they cancel out]

     

    60000 + x = 3*41000

    60000 + x = 123000

    x= 123000 - 60000

    x= 63000

     

    therfore you can change the delay value accordingly.

     

    Message was edited by: lp4nb

Actions

More Like This

  • Retrieving data ...

Bookmarked By (0)