The role of signaling in quality of service enabled networks

In this article we identify the common building blocks that enable some net works to provide better than best-effort transfer guarantees to the traffic they carry. We consider the role signaling plays in such a network and arg ue in favor of pinned routes, with a highly efficient pinning process, to i mprove network stability and to ease the task of maintaining QoS guarantees in the face of changing network characteristics, including failures; the u se of broad QoS classes to determine the path that a particular flow should follow through the network; and providing the flexibility of specifying th e detailed QoS for the flow, if needed, at any arbitrary time during the li fe of the flow. We conclude that a flexible signaling architecture is an es sential enabling component of any QoS-aware network. We present an overview of the design and implementation of UNITE, as an example of a signaling ar chitecture that embodies these attributes. More generally, we consider the relationship between QoS-related signaling and other protocols and mechanis ms that may form part of an overall QoS-enabled network and service infrast ructure.