Modeling the Internet infrastructure is a challenging endeavor. Complex interactions between protocols, increasing traffic volumes and the irregular structure of the Internet lead to demanding requirements for the simulation developer. These requirements include implementation detail, memory efficiency and scalability, among others. We introduce a simulation model of the Border Gateway Protocol that we call BGP++, which is built on the popular ns-2 simulation environment. A novel development approach is presented that incorporates the public domain routing software GNU Zebra in the simulator. Most of the original software functionality is retained, while the transition to the simulation environment required a manageable amount of effort. Moreover, the discussed design inherits much of the maturity of the original software, since the later is only minimally modified. We analyze BGP++ features and highlight its potential to provide significant aid in BGP research and modeling.