Shortly after signing his first pro contract, Porter, a cornerback who was taken 40th overall in April's draft, took the field for the Saints' fourth practice of training camp.
"I'm glad the whole ordeal is over and I can come out here and develop chemistry with me teammates," Porter said.
Johnson hadn't practiced since Thursday's opening of camp because of a left ankle injury that occurred during the offseason.
Johnson played in 14 games for New Orleans last season, starting 12, and caught 48 passes for 378 yards and two touchdowns.
He played receiver at Yale before switching to tight end in the NFL and led San Francisco in receiving yards in 2004, when he had 82 catches for 825 yards, including a pair of touchdowns.
With Porter's arrival, the only Saints draft choice remaining unsigned and out of camp was former Southern California defensive tackle Sedrick Ellis, the seventh overall pick.
"It's a great thing that I didn't miss too many practices," Porter said. "I know there's stiff competition as well ... but I'm definitely keeping up to speed (with) what the coaches are throwing at me."
Porter, who grew up a Saints fan in Port Allen, La., was a four-year starter in college at Indiana and was defensive captain and a first-team All-Big Ten selection his senior year. He is expected to compete for playing time this season, particularly on passing downs when defenses tend to use five or six defensive backs.
He intercepted 16 passes in his college career, including six in 2007.
He was also the only player in Indiana history to return a punt, interception and fumble for a touchdown in addition to setting an Indiana all-time record with 413 yards in interception returns.