Chelsea paid £7.5m for his services in the summer of 2001 and he played for two seasons at Stamford Bridge before being loaned out to Middlesbrough in 2003.
That move was made permanent the following season, but one year later he switched to Liverpool on another free transfer.
He spent two years on Merseyside and played in the Reds 2-1 Champions League final defeat by AC Milan in 2007.
He left for Marseille at the end of that season and spent two seasons at the Stade Velodrome before opting to leave at the end of last season.
He will provide cover in midfield for Sunderland, who are short of numbers in the middle of the park after Dean Whitehead, Grant Leadbitter and Carlos Edwards were sold in the summer while Teemu Tainio was allowed to join Birmingham on loan.
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