10月9号 RS LAB PASS 关于EIGRP METRIC计算的一点分享

jlp999

一直不清楚EIGRP 的 cost 计算:

在这做个总结, 这个是EIGRP的基础知识, 属于实验考试范围.
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The formulae for calculating EIGRP metric is:

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metric = [K1 * bandwidth + (K2 * bandwidth) / (256 - load) + K3 * delay] * [K5 / (reliability + K4)]

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k1=bandwidth

k2=load

k3=delay

k4=reliability

k5=MTU

usuallly only Bandwidth and Delay are considered for Bandwidth calculation (by default) . so K1 = 1 and K3 = 1 and rest all are Zero. (although you can change these metric weights (k- values))

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applying that on the formula.

the Metric would be

256 *( (k1 * BW) + (K3 * Delay))

-----------------------------------

For example:

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k1=bandwidth  1000 k

k2=load           10

k3=delay         2000

k4=reliability   255

k5=MTU          1500

so by default the cost shoud be :

256 *( (1 * 1000) + (1 * 2000)) == 768000

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if change the default value for k1-k5 to all 1 (metric weights 0 1 1 1 1 1)

then the cost shoud be :

Metric = 256*[(1 * 1000) + (1 * 1000)/(256-10) + (1*2000)]*(1/(255 + 1)) == 3004

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