Experimental Study of BGP Protocol Functioning in A Multiprotocol Virtualized Environment Using The GNS3 Emulator

Abstract

The article presents the results of an experimental study of the stability and convergence dynamics of the BGP protocol in a heterogeneous multiprotocol environment. The relevance of the topic is due to the increasing complexity of global networks and the need to ensure continuous routing between autonomous systems while simultaneously supporting IPv4 and IPv6 stacks. The aim of the work is to quantify the convergence and stability trade-offs of MP-BGP under four controlled failure modes in a reproducible dual-stack GNS3 testbed. To achieve this goal, a virtualized research environment was created in GNS3, which allows modeling interdomain interacting routers, mitigating the risks inherent in real BGP experiments. The methodology involved four scenarios: disabling the main eBGP channel, switching between IPv4 and IPv6, applying route-map policies, and analyzing the flap effect between autonomous systems. As a result, the impact of the Hold Time and Keepalive parameters on convergence time and session stability was determined. It was demonstrated that reducing Keepalive from 60 s to 5 s decreases per-cycle recovery time from ≈7– 8 s to 1.75 s (95% CI [1.61 – 1.89]), but increases peer flap frequency by a factor of 3, revealing a quantifiable stability – convergence trade-off. Inbound route-map filtering reduced the accepted prefix count by 87% (from 31 to 4), with convergence completing within 2 s and no session disruption. The practical value of this work lies in the development of an approach to secure inter-domain routing testing using GNS3, which provides reliable reproduction of BGP behavior in IPv4/IPv6 multiprotocol scenarios. The findings demonstrate that timer tuning and inbound filtering are practically effective for controlling convergence behavior in dual-stack environments, and establish a reproducible GNS3-based testbed that can be directly extended to evaluate Route