The Vikings had Frank Walker in for a workout this morning at Winter Park and signed the cornerback once he passed a physical. Walker received a one-year deal for the veteran's minimum, which would be $755,000 for the full season.

Walker's addition gives the Vikings four healthy cornerbacks for Sunday's game against Dallas. The team is shorthanded with Cedric Griffin having been lost for the season in Monday's game against the Jets because of a torn anterior cruciate ligament in his right knee. Chris Cook missed the game after having arthroscopic surgery for a torn meniscus in his left knee. It's not certain if Cook will be able to play Sunday.

Walker, 5-11, 200 pounds, spent last season with the Baltimore Ravens and also has played for the Giants and Packers during his seven-year career. He is practicing with the Vikings today and wearing No. 41.

Walker, 29, appeared in 14 regular-season games for Baltimore last year and finished with one interception and four pass breakups. He started a game late in the regular season because of injuries in the secondary and also played in both the Ravens' playoff games, starting in the loss to Indianapolis.

The Ravens did not bring back Walker this season and he was not signed by a team. Walker worked out with New Orleans on Tuesday. He also had worked out for the Colts, Dolphins and Titans. The Bears expressed interest in Walker but did not bring him in for a workout.

Walker is a physical corner and might be best suited for man-to-man coverage. He also can play in nickel and dime defenses and contribute on special teams.