Jo-Lonn_DunbarJo-Lonn Dunbar was slated to be the Rams’ starting outside linebacker in Week 1. Instead, he’ll spend the first month warming the bench.

The former Boston College star has been suspended four games for violating the NFL’s performance-enhancing drug policy, the league announced Wednesday.

Dunbar will be allowed to participate in both games and practices during the preseason, but he will not be eligible to play in a regular-season game until Week 5 against Jacksonville.

Since breaking into the league as an undrafted free agent in 2008, Dunbar has seen his production improve exponentially each year. He posted career highs for tackles (115) and sacks (4.5) last season — his first in St. Louis — while also intercepting two passes and forcing a pair of fumbles.

While at BC, Dunbar amassed 262 career tackles and earned second-team All-ACC honors as a senior.