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Transport Agent – (ETP-Agent)
One of the main features of the NetQoS system is to provide a way for managing QoS at various levels of the communication stack (Transport, Network, Data Link…). However, the existence of a variety of systems available for providing QoS at each of the considered layers is an element that contributes to its complexity.
In order to address these various technologies while maintaining a certain level of abstractions in the APA component, the QoS policies are described in an intermediate NetQoS policy language. Indeed, the low level operational policies that represent the decision taken by the APA component and dispatched by the PEM are described in a technology independent grammar. 
The Transport Agent represents the final step in policy enforcement at the Transport Level. Depending on the type of modular transport to be configured, the APA Policy Enforcement Manager contacts the adequate Transport Agent instance.
In order to be able to target a wide diversity of existing systems, the adaptor design principle has been applied. The ETP Agent represents the instance of such adaptor component at the Transport level.
The ETP-Agent is responsible for translating NETQoS Transport Operational Policies into system specific ETP Composition Descriptions. After this translation, it contacts the Transport entities for deployment. 
The Transport agent supports following Transport types Recognised Micro Protocols are the following: - Shaper
- TFRC
- SACK – Error Control
- PR – Partial reliability
- D-PR – Differentiated Partial Reliability for RTP profiles
- TD-PR – Time Dependant Differentiated Partial Reliability for RTP profiles
In order to allow an ETP instance executing on the end user’s machine for a given connection to be dynamically reconfigured by the NetQoS system at run time, the ETP Agent will be provided with an helper module in the management plan of the ETP instance. The role of the ETP Agent Interface module is to provide a hook for the ETP Agent to be able to interact with the running ETP instance.
The ETP Agent Interface will be located in the Management plan of the ETP instances running on the end user’s machines. The minimal ETP stack in order to allow dynamic configuration of the ETP instance by the ETP agent interacting with the NetQoS system is presented here below.The ETP Agent Interface will be located in the Management plan of the ETP instances running on the end user’s machines. The minimal ETP stack in order to allow dynamic configuration of the ETP instance by the ETP agent interacting with the NetQoS system is presented here below. 
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