### Solutions
Solution 1:
Metric Calculation from Router A to Router B
- Bandwidth: 100 Mbps = 100,000 Kbps
- Delay: 1000 microseconds
\[ \text{Metric} = \left( \frac{10^7}{100,000} \right) + \left( \frac{1000}{10} \right) \times 256 \]
\[ \text{Metric} = (100) + (100) \times 256 \]
\[ \text{Metric} = 100 + 25600 \]
\[ \text{Metric} = 25,700 \]
Solution 2:
Metric Calculation from Router A to Router C
- Bandwidth: 100 Mbps = 100,000 Kbps
- Delay: 500 microseconds
\[ \text{Metric} = \left( \frac{10^7}{100,000} \right) + \left( \frac{500}{10} \right) \times 256 \]
\[ \text{Metric} = (100) + (50) \times 256 \]
\[ \text{Metric} = 100 + 12800 \]
\[ \text{Metric} = 12,900 \]
Solution 3:
Metric Calculation from Router B to Router C
- Bandwidth: 50 Mbps = 50,000 Kbps
- Delay: 1500 microseconds
\[ \text{Metric} = \left( \frac{10^7}{50,000} \right) + \left( \frac{1500}{10} \right) \times 256 \]
\[ \text{Metric} = (200) + (150) \times 256 \]
\[ \text{Metric} = 200 + 38400 \]
\[ \text{Metric} = 38,600 \]
Solution 4:
Metric Calculation from Router A to Router C via Router B
- A to B Metric: 25,700 (from Solution 1)
- B to C Metric: 38,600 (from Solution 3)
The total metric from A to C via B:
\[ \text{Total Metric} = 25,700 + 38,600 \]
\[ \text{Total Metric} = 64,300 \]
Solution 5:
Path Preference from Router C to Router A
- Direct Metric (C to A): 12,900 (from Solution 2)
- Metric via B (C to A): 64,300 (from Solution 4)
Preferred Path:
Router C will prefer the direct path to Router A with a metric of 12,900 over the indirect path via Router B with a metric of 64,300.
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### Summary
- Direct paths generally have lower metrics because they involve fewer hops, less delay, and potentially higher bandwidths.
- EIGRP prefers routes with the lowest metrics, combining bandwidth and delay into a single metric value.
- Understanding EIGRP metrics is essential for optimizing and troubleshooting network paths in EIGRP environments.
This exercise provides practical calculations that reflect real-world scenarios, helping to solidify your understanding of how EIGRP cost calculation works.
