The Graceful Restart (GR) is used to further improve system reliability. GR is the extension of ISIS and RSVP protocols. During the rebooting of the local router, the neighbor router forwards packets continuously and does not recalculate routes. After the local router is restarted, the neighbor router sends all the routing information to the local router and helps the local router to restore network topology. GR only maintains forwarding table and does not require the local router to backup routing information.