Anderson started all 16 games with Chicago last year after spending his other seven NFL seasons with the Carolina Panthers. He had 102 tackles and four sacks for the Bears.
The Panthers drafted Anderson in the third round from Virginia Tech in 2006. He has started 69 of his 110 games with 556 tackles, 12 sacks, three interceptions and eight fumble recoveries. He had a franchise-record 145 tackles for Carolina in 2011.
Harrison spent last season on the Patriots reserve-non-football injury list after signing as a rookie free agent out of Rutgers last May.
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