Operation Manual – IP Routing-GR OverviewH3C S5500-EI Series Ethernet Switches Chapter 2 GR Overview2-2z GR Session: A Graceful Restart session, which is the negotiation between the GRRestarter and the GR Helper. A GR session includes restart notification andcommunications across restart. Through this session, GR Restarter and GRHelper can know the GR capability of each other.z GR Time: The time taken for the GR Restarter and the GR Helper to establish asession between them. Upon detection of the down state of a neighbor, the GRHelper will preserve the topology and routing information sent from the GRRestarter for a period as specified by the GR Time.2.3 Graceful Restart Communication ProcedureConfigure a device as GR Restarter in a network. This device and its GR Helper mustsupport GR or be GR capable. Thus, when GR Restarter restarts, its GR Helper canknow its restart process.Note:In some cases, GR Restarter and GR Helper can replace with each other.The communication procedure between the GR Restarter and the GR Helper works asfollows:1) A GR session is established between the GR Restarter and the GR Helper.Figure 2-1 A GR session is established between the GR Restarter and the GR HelperAs illustrated in Figure 2-1, Router A works as GR Restarter, Router B, Router C andRouter D are the GR Helpers of Router A. A GR session is established between the GRRestarter and the GR Helper.
