In a large skillet over medium heat, sauté the onion, carrot, and celery for about ten minutes until translucent. Add the red pepper, fennel seeds, and sausage. Mix well until the sausage is no longer pink. Add the pancetta and after a couple of minutes, the white wine. Raise the heat and cook for a few minutes, allowing the alcohol to evaporate. Reduce heat to low, add salt and cover. Cook for about 30 minutes.
Meanwhile, wash the broccoli rabe, clean, and chop coarsely. When the sausage sauce is well cooked, add the broccoli rabe, cover and cook 2 minutes.
Bring a large pot of salted water to a boil. Cook the pasta until al dente, drain it, reserving a little cooking water.
Add the pasta to the pan with the sausage and broccoli. Mix well, adding some water if it seems dry.