Sullivan, 31, is a former sixth-round pick of the Vikings back in 2008. He had two years remaining on his six-year, $25.6 million contract when the Vikings cut him loose coming out of the preseason after they were unable to find a trade partner.
The Redskins signed him to a contract a few weeks into the regular season and finished out the year in Washington.
Sullivan missed all of 2015, due to multiple back surgeries.
In 2016, Sullivan appeared in 13 games for the Redskins and played a total of 98 snaps for the Redskins, according to Pro Football Focus.
We had him featured in our Top 50 Available Free Agents list.