3Com Switch 4800G 24-Port Configuration Manual page 249

Figure 65 Restarting process for the GR Restarter
Router D
Router A
Router B
GR helper
GR capable GR session
The administrator restarts GR Restarter
or GR Restarter is operating abnormally
As illustrated in Figure 65. The GR Helper detects that the GR Restarter has
restarted its routing protocol and assumes that it will recover within the GR Time.
Before the GR Time expires, the GR Helper will neither terminate the session with
the GR Restarter nor delete the topology or routing information of the latter.
3 GR Restarter signaling to GR Helper
Figure 66 The GR Restarter signals to the GR Helper(s) after restart
Router D
Router A
Router B
GR helper
Signals to establish GR session
As illustrated in Figure 66, after the GR Restarter has recovered, it will signal to all
its neighbors and will reestablish GR Session.
4 The GR Restarter obtaining topology and routing information from the GR Helper
Graceful Restart Communication Procedure
GR helper
GR restarter
Router C
GR helper
GR helper
GR restarter
Router C
GR helper
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