## 6 Methodology and Performance Metrics Measurement  
The network topology for this study was meticulously designed using GNS3, incorporating thirteen Cisco routers configured with OSPF, EIGRP, and BGP protocols to simulate a complex network environment. Two virtual machines were deployed on VMware to represent end-user devices, all configured with IPv6 to evaluate the latest iteration of the Internet Protocol. Detailed packet-level analysis was performed using Wireshark, which allowed for an in-depth examination of routing protocol behavior. IPerf3 was employed to generate traffic and measure critical performance metrics such as network delay, jitter, and packet loss across various scenarios.  
Load-sharing and link-failover mechanisms were configured to assess how OSPF and EIGRP manage traffic distribution and handle link failures. The experiments systematically varied parameters such as network size, traffic load, and link conditions to provide a comprehensive understanding of the strengths and weaknesses of OSPF and EIGRP, particularly in comparison to BGP within an IPv6 framework. The results were meticulously analyzed to evaluate the performance and suitability of each protocol for specific network conditions, offering valuable insights for network administrators and designers in making informed decisions about protocol selection and network architecture.  
Performance metrics were carefully measured as follows:  
1. Network delay:  
The total network delay was calculated by summing propagation, transmission, queuing, and processing delays, as in Equation (1):  
\[TotalDelay=d_{prop}+d_{trans}+d_{queue}+d_{proc} \tag{1}\]  
where \(d_{prop}\) is the propagation delay, \(d_{trans}\) is the transmission delay, \(d_{queue}\) is the queuing delay, and \(d_{proc}\) is the processing delay.
2. Network jitter:  
Measured in milliseconds, jitter is represented as the average deviation from the mean delay calculated in Equation (2).  
\[J=\sqrt{\frac{1}{N}\sum_{i=1}^{N}(D_{i}-\bar{D})^{2}} \tag{2}\]  
where \(J\) is jitter, \(1/N\) is the total number of measured packets, \(D_{i}\) is a delay of the \(i\)-th packet, and \(\bar{D}\) is the average delay of all the measured packets. The packet loss (\(P_{loss}\)) percentage.  
3. Packet loss: The packet loss percentage was calculated using Equation (3): \[P_{loss}=\frac{Number\ of\ Lost\ Packets}{Total\ Number\ of\ Sent\ Packets}\times 100\] (3)  
4. Convergence Time: This metric refers to the time taken to detect and recover from a link failure, given by Equation (4): \[T_{convergence}=Time_{recovery}-Time_{failure}\] (4)  
In evaluating these metrics, the study employed a structured experimental setup to simulate various network conditions, load-sharing configurations, and link-failure scenarios. Rigorous testing and statistical analysis were conducted to assess the efficiency of EIGRP and OSPF, providing a comprehensive understanding of their real-world application and performance in load-sharing and link-failover systems. The findings contribute to a better grasp of the strengths and limitations of each protocol, offering guidance for enhancing network efficiency and reliability.  
There are three use cases of load-sharing and link-failover systems: