Link States, Interface Hotswap

Uses the Linux Netlink interface to improve robustness and availability of sfptpd when used over Linux bonded interfaces.

• As long as there is a link available, sfptpd will remain active in the PTP_SLAVE state.
• If all bonded links are down sfptpd will remain active in the PTP_LISTENING state and will activate the no-interface alarm.
• When a failed bond link is restored, sfptpd will resume, changing to a PTP_SLAVE state if the previous state was PTP_LISTENING.
• If an adapter/interface is swapped out/in, sfptpd will identify the new interface(s) and continue.