Johnson, 28, wound up signing on with the Seahawks as an undrafted free agent out of Boise State back in 2011. He spent four years in Seattle before signing a two-year, $2.5 million with the Redskins last year.
However, Washington elected to cut him loose back in March. Johnson later signed on with the Chiefs in August but was unfortunately among their final roster cuts coming out of the preseason.
In 2015, Johnson appeared in 14 games and recorded 27 tackles. Pro Football Focus has him down for playing 195 total snaps last year.
Allen, 34, is a former fourth-round pick of the Buccaneers back in 2004. He spent six year in Tampa Bay before signing on with the Steelers back in 2010.
Allen has been testing the open market as an unrestricted free agent, but this is the first reported interest in him since free agency got underway back in March.
In 2015, Allen appeared in 13 games for the Steelers and recorded 79 tackles, four sacks, an interception, two forced fumbles and eight pass defenses.