In IPv6 environment,when we have many routers sending out router advertisements,one of these routers will be configured as the default router. When this default router is removed from the network,how do we determine that it is no longer reachable? Does "neighbour unreachability detection" handle this ,detect it within 38 seconds and delete that router entry automatically from the default router list? I notice that the entry remains in the default router list as long as the router "lifetime " value doesnt expire. I would like to know what is the idea behind having that entry if the router is not in the network?
Thanks