EPC Demonstration Enablers

A set of additional components are provided together with the Release 1 of the OpenEPC project. Although many of these are not essential for the functionality, they are performing important roles not only enhancing, but also showcasing the advantages of an EPC architecture.

1. Modified ISC-DHCP

The  ISC-DHCP server has been modified and is provided to fit with the MAG requirements. The IP allocation operations have been deferred from the internal mechanisms to the external MAG operations. Only the initial IP address allocation actually triggers an event and subsequent refreshes are cached at the DHCP server, with unidirectional events being pushed to the MAG.

2. Video Streaming Application with Adaptive Bitrate

To demonstrate how and application would benefit from receiving hand-over information from the EPC IP connectivity provider, we have developed a simple and effective demonstrator which can illustrate the effect of switching between Access Networks with different bandwidth and latency characteristics.

At the front of this application, a  gstreamer script provides video streams with various from a single live video source, like a webcam. This acts as a Content Provider for an Application Function (Media Delivery Function) controlled through a SIP interface that is capable of relaying the incoming video streams to unicast/multicast IP addresses as specified in the SIP's message SDP. The main feature of this application function is that it reacts to callbacks from the PCC to adapt the bitrate to the conditions of the link or to user policies. The AF is prepared to react to the following events:

• PCC Session Termination: ends the specified media session.
• PCC QoS change: changes the session bandwidth to a higher or lower value.
• PCC Loss: the streaming is paused.
• PCC Recovery: the streaming session is resumed.

3. HTTP interceptor (Squid + Rx_auth)

Besides serving applications which are specifically designed to inter-work with it, the EPC architecture is capable to accustom also for Over-The-Top (OTT) applications. In order to demonstrate such a scenario where a Deep-Packet-Inspection (DPI) analyzes transparently the traffic, we have developed a simple look-alike demonstrator by reusing the Squid HTTP proxy and hooking through a built-in feature, the capability to use an external Access Control List (ACL) provider for authorizing web accesses.

The  Squid HTTP proxy is using the program Rx_auth as an external ACL function to check if the access is granted or not for a specific HTTP request. Rx_auth links Squid to the Client_Rx module. For every source IP and service (domain name from the URL) a distinct AF session will be considered. The use-case of the HTTP interceptor can be resumed to the following steps: a) Squid is started, b) the user adds in its browser the Squid HTTP proxy settings (the IP and port that Squid is listening on); alternatively, a firewall rule on the PDN-Gw could redirect all web-browsing traffic through the HTTP proxy, c)based on the used service and the policies associated at the PCRF, the access will be granted or not for a specific site with specific throughput and priority rules being pushed in the PCC architecture.

Limitations:

• the Rx_auth ACL mechanism only triggers the start event, but not the end of the session

4. IMS Audio/Video Calls over EPC

For the purpose of providing telephony services in the context of LTE networks, IMS is being regarded currently as a premier choice. To demonstrate the good integration and inter-operability between the IMS and EPC layers, the  Open Source IMS Core Project has been extended and is fully supported for the purposes of experimentation with OpenEPC.

The setup consists of an  Open IMS Core testbed and two instances of the  myMONSTER IMS clients for two subscribers. For service authorization and resource reservation the Rx interface of the P-CSCF is enabled and configured to use the PCRF from OpenEPC. When the users register/deregister or make/modify IMS sessions the P-CSCF requests enabling/disabling of IP flows. Based on the user subscription profile, the policies from OpenEPC will grant the access with specific throughput and priority. In this use-case the users can make audio/video calls. Then the session can be modified to enable/disable video flows in the call. The two parties can put the call on hold and resume the call. After some time the call is eventually torn-down and the allocated IP-CAN resources for the call are freed.