Large-Scale IP Network Solutions (CCIE Professional Development)

Deploying QoS in Large Networks

As usual, the approach is to perform computational expensive functions at the perimeter of the network, liberating the core and distribution networks to focus on aggregation and forwarding functions. Hence, it is recommended that you deploy policy control functions on the network perimeter and incorporate congestion avoidance, in the form of WRED, at the core. If traffic-shaping and/or rate-limiting is required at the network perimeter, CAR represents the most flexible solution.

This is not to say that congestion-management capabilities (such as priority or custom queuing) will not find application in the network, but they should be used sparingly and with caution, particularly on high-speed links.

In its current ...