SonicWALL TZ 190 Manuale Utente

. SonicOS’s BWM is a perfectly effective solution for fully autonomous 

private networks with sufficient bandwidth, but can become somewhat less effective as more 
unknown external network elements and bandwidth contention are introduced. Refer to the 

 in the 

 for a description of contention 

issues.

To provide end-to-end QoS, business-class service providers are increasingly offering traffic 
conditioning services on their IP networks. These services typically depend on the customer 
premise equipment to classify and tag the traffic, generally using a standard marking method 
such as DSCP. SonicOS Enhanced has the ability to DSCP mark traffic after classification, as 
well as the ability to map 802.1p tags to DSCP tags for external network traversal and CoS 
preservation. For VPN traffic, SonicOS can DSCP mark not only the internal (payload) packets, 
but the external (encapsulating) packets as well so that QoS capable service providers can offer 
QoS even on encrypted VPN traffic.

The actual conditioning method employed by service providers varies from one to the next, but 
it generally involves a class-based queuing method such as Weighted Fair Queuing for 
prioritizing traffic, as well a congestion avoidance method, such as tail-drop or Random Early 
Detection. 

The following sections detail the 802.1p standard and DSCP QoS.