CARLTON may target out-of-contract Fremantle defender Chris Tarrant in next month's exchange period.

The former Magpie has come to the end of a four-year deal with Fremantle and has informed the club that he wants to be traded back to Melbourne.

Carlton coach Brett Ratten said Tarrant could bolster a backline that looked vulnerable at times this season.

"If Chris is coming home and wants to come home, then I think he would seem to be a fairly good fit for our club and where we've got that deficiency," he told afl.com.au.

"What he's done to go back from being a forward and play on talls and smalls, I think his record over the last two years as a backman has been outstanding.

"Someone that could play at both ends would be preferable but I think we just need another tall defender."

Ratten also confirmed the club's interest in Jared Brennan, who has played his last game for the Brisbane Lions and has already been linked to Gold Coast.

At 195cm, Brennan has a proven ability to play in the forward line, midfield or backline.

"I think when a player of his calibre comes out, if you've got room in your salary cap and that opportunity arises, I think you really take it seriously," Ratten said.

"I think what he can do as a player is turn a game and I suppose some of those battles we have had [against Brisbane] ... were really tight tussles and he's one that really did cause a bit of a problem in the coach's box for me.

"I think in one of the games he scored something like four goals in about 15 minutes and we thought, 'He's on fire, how do we stop him?'

"His versatility is something I think every club would look at."

However, in gaining either player, Carlton could lose its own with Andrew Walker having met with Adelaide.

The Crows contacted Ratten to ask if they could speak to Walker, who has two years remaining on his Carlton contract.

Ratten said he would entertain trading Walker for the right return, but stressed that the Blues' preference was to retain the 24-year-old.

Walker, Carlton's first-round draft selection in 2003 (No.2 overall), has played 103 games in seven seasons despite his injury battles.

"We spoke with Andrew and explored the possibility of another club and where he sits," Ratten said.

"It's something we'll investigate and see what's out there.

"We've put seven years into Andrew. He's starting to maybe blossom in his football. We've seen that through the year before he hurt his shoulder."

Ratten also said emerging ruckman Sam Jacobs, in the sights of clubs from his native South Australia, was a required player and the coach expected those contract negotiations to start next week.

Follow our complete coverage of the 2010 AFL exchange period from October 4-11. No trades are official until paperwork has been accepted by the AFL and formally recognised after 2pm on Monday, October 11.

Join the AFL trade conversation on Twitter: use #tradeweek in your tweets.