1) The routes with the same RT which is configured in the local vpn-instance, go to next step to judge.
2) All routes meet condition 1), the routes with the same RD which is configured in the local vpn-instance, will be installed.
3) All routes meet condition 1), the routes with different RD which is configured in the local vpn-instance, but is the “best” route, will be installed; otherwise will not be installed.
