Minimum prefix length of Route Information in RA.
Route Information w/ prefix smaller than this variable shall be ignored.
Functional default: 0 if accept_ra_rtr_pref is enabled. -1 if accept_ra_rtr_pref is disabled.
Nb: per interface setting (where “interface” is the name of your network interface); “all” is a special interface: changes the settings for all interfaces.
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