A shouldered connector pin socket is shown having an open channel formed in the face surface of a wall member of a circuit breaker housing. Numerous other aspects are provided. Otherwise, traffic may be communicated for each of the plurality of classes in an amount proportional to the respective committed information rate for a particular class and the available aggregate bandwidth. The system includes a sludge mat dislodging member that moves along the filter bed surface, preferably on but substantially not inside the filter bed, to disruptdislodge the sludge mat andor prevent formation of the sludge mat.