Classification

Classification is necessary as a first step so that traffic in need of management can be identified. SonicOS Enhanced uses Access Rules as the interface to classification of traffic. This provides fine controls using combinations of Address Object, Service Object, and Schedule Object elements, allowing for classification criteria as general as all HTTP traffic and as specific as SSH traffic from hostA to serverB on Wednesdays at 2:12am.

SonicOS on SonicWall NSA series appliances has the ability to recognize, map, modify, and generate the industry-standard external CoS designators, DSCP and 802.1p (refer to the 802.1p and DSCP QoS).

When identified, or classified, it can be managed. Management can be performed internally by SonicOS’s BWM, which is perfectly effective as long as the network is a fully contained autonomous system. When external or intermediate elements are introduced, such as foreign network infrastructures with unknown configurations, or other hosts contending for bandwidth (for example, the Internet) the ability to offer guarantees and predictability are diminished. In other words, as long as the endpoints of the network and everything in between are within your management, BWM will work exactly as configured. Once external entities are introduced, the precision and efficacy of BWM configurations can begin to degrade.

But all is not lost. When SonicOS classifies the traffic, it can tag the traffic to communicate this classification to certain external systems that are capable of abiding by CoS tags; thus they too can participate in providing QoS.

NOTE: Many service providers do not support CoS tags such as 802.1p or DSCP. Also, most network equipment with standard configurations will not be able to recognize 802.1p tags, and could drop tagged traffic. Although DSCP will not cause compatibility issues, many service providers will simply strip or ignore the DSCP tags, disregarding the code points. If you wish to use 802.1p or DSCP marking on your network or your service provider’s network, you must first establish that these methods are supported. Verify that your internal network equipment can support CoS priority marking, and that it is correctly configured to do so. Check with your service provider — some offer fee-based support for QoS using these CoS methods.