Dependability Evaluation in a Convergent Network Service using BGP and BFD Protocols

The infrastructure necessary to support convergent network services is increasingly more complex than the usual communication networks. A network device must be able to quickly detect any communication failure between adjacent devices for the upper-layer protocol to be able rectify this failure and prevent any interruptions in services. Convergent networks use Hello routing protocol from the upper layer to detect failures. The detection period, dependent on issues intrinsic to the protocol and the arrangement of the network configuration, can lead to high downtimes in case of unavailability of the main circuit and of switch to the backup circuit. In this context, considering a real corporate network in a production environment, there is the need to carry out experiments aimed at obtaining a scenario that can offer the lowest downtime and, consequently, a greater network availability. This work is aimed at carrying out an inferential performance assessment through a paired before-and-after comparison in order to obtain the best convergence condition for a corporate network and consequently offer greater availability. For that aim, we have proposed a Continuous-Time Markov Chain (CTMC) that represents convergent network architectures considering the Border Gateway Protocol (BGP) and Bidirectional Forwarding Detection (BFD) protocol for supporting availability evaluation. In addition, we presented a closed-form equation derived from the proposed CTMC for calculating the availability of critical warm standby components by system considering its size. The work also presents a sensitivity analysis of network availability as a result of fail over time. Our approach has proven to be feasible, and it highlights the most appropriate scenarios, supporting network architects at design time.