Scheduled to become an unrestricted free agent, Lankster had 20 tackles on special teams last season.
He's a former Buffalo Bills seventh-round draft pick.
Walls was scheduled to become a restricted free agent.
He started three games last season and registered a career--high 24 tackles on defense with five pass deflections.
A former Notre Dame player who went undrafted, Walls was signed by the Atlanta Falcons in 2011.
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Aaron Wilson covers the Ravens for The Baltimore Sun