▁Ne igh bor ▁Disc overy ▁Pro tocol ▁( ND ) ▁for ▁IP v 6 ▁through ▁the ▁Sec ure ▁Ne igh bor ▁Disc overy ▁protocol ▁( S END ). ▁ ▁The ▁R PK I ▁architecture ▁is ▁documented ▁in ▁R FC ▁ 6 4 8 0 . ▁ ▁The ▁R PK I ▁specification ▁is ▁documented ▁in ▁a ▁spread ▁out ▁series ▁of ▁R FC s : ▁R FC ▁ 6 4 8 1 , ▁R FC ▁ 6 4 8 2 , ▁R FC ▁ 6 4 8 3 , ▁R FC ▁ 6 4 8 4 , ▁R FC ▁ 6 4 8 5 , ▁R FC ▁ 6 4 8 6 , ▁R FC ▁ 6 4 8 7 , ▁R FC ▁ 6 4 8 8 , ▁R FC ▁ 6 4 8 9 , ▁R FC ▁ 6 4 9 0 , ▁R FC ▁ 6 4 9 1 , ▁R FC ▁ 6 4 9 2 , ▁and ▁R FC ▁ 6 4 9 3 . ▁S END ▁is ▁documented ▁in ▁R FC ▁ 6 4 9 4 ▁and ▁R FC ▁ 6 4 9 5 . ▁ ▁These ▁R FC s ▁are ▁a ▁product ▁of ▁the ▁I ET F ' s ▁sid r ▁working ▁group , ▁and ▁are ▁based ▁on ▁a ▁threat ▁analysis ▁which ▁was ▁documented ▁in ▁R FC ▁ 4 5 9 3 . ▁These ▁standards ▁cover ▁B GP ▁origin ▁validation , ▁while ▁work ▁on ▁path ▁validation ▁( B GP SE C ) ▁is ▁under way . ▁Several ▁implementations