SDN LTE Evolved Packet Core - by Preethi P. Y

SDN EPC is an implementation of Long Term Evolution Evolved Packet Core (LTE EPC) using design principles of SDN. It simulates the working of a typical EPC for handling signalling and data traffic.

Using SDN:
With an expansion in the number of versatile clients and activity, portable system administrators are thinking that it's hard proportional their radio and core systems. Further, network appliances are costly to acquire and redesign and are hard to adjust and program for new administrations. With SDN, the control and information planes of the packet core can be isolated, empowering less expensive bundle entryways in the information plane, and a savvy centre system controller to deal with the flagging and administration capacities.

Architecture:

A: Traditional LTE Core architecture

B: SDN-based LTE EPC architecture

The solution with SDN :

A common SDN-based EPC is a partition of control and data planes for the packet core Gateways—SGW ( serving gateway ) and PGW ( packet data network gateway ). The MME ( mobility management entity), is only a control plane entity. So the MME, SGW-C and PGW-C run as applications over an SDN controller. The SGW-D and PGW-D are acknowledged as SDN (OpenFlow) switches which forward packets based on the rules introduced by the controller. The HSS is actualized as a different application utilized by MME, though the PCRF (Policy and Charging Rules Function) is a different application utilized by PGW.

The setup :

Modules involved :

1. Mobility Management Entity - SDN architecture centralizes the control plane functionality of packet core, thereby eliminating the use of mobility management protocols and reducing mobility-related signalling costs.
2. Home Subscriber Server - Database for packet core.
3. Serving Gateway(SGW)- The SGW resides in the user plane where it forwards and routes packets to and from the element of LTE and packet data network gateway.
4. Packet Data Network Gateway (PGW)- The PGW acts as the interface between the LTE network and other packet data networks, such as the Internet etc.,
5. Radio Access Network Simulator - RAN is a multithreaded simulator.

Importance of each entity :

• Mobility Management Entity (MME): SDN architecture centralizes the control plane functionality of EPC thereby eliminating the use of mobility management protocols and reducing mobility-related signalling costs. The architecture utilizes the global network view feature of SDN for mobility management. The results quantify the performance of the SDN architecture in terms of signalling cost, tunnelling cost, handover latency and scalability.
• The Home Subscriber Server is the main database which goes about as a database in EPC.
• Serving Gateway: The SGW dwells in the client plane where it advances and courses bundles to and from the eNodeB and parcel information organize passage (PGW).

• Packet Data Network Gateway: The PGW acts as the interface between the LTE network and other packet data networks, such as the Internet.

Implementation :

We have simulated the working in RAN simulator. The RAN simulator is coded in C/C++ whereas the controller used is the floodlight controller which uses Java. Hence the experience using both of them is a pre-requisite.

Let's get started with the RAN simulator. The steps involved in the simulator are :

1. Authentication: In this step, exchange of authentication messages takes place between RAN and the MME via default switch using the UDP. Also, the MME communicates with HSS which in turn queries the database MySql using JDBC the driver.
2. Passage setup: After effective validation, the MME starts tunnel setup methodology. Amid this progression, trade of control messages happens among MME, SGW-C and PGW-C by means of Java object calls. Furthermore, OpenFlow rules are introduced into the concerned information plane switches, along these lines, setting up the passage.
3. Data transfer: This step is optional. During this step, iperf3 at RAN generates data in the form of TCP traffic which flows through the EPC to the sink.
4. Detach: During this progression, the control applications (MME, SGW-C and PGW-C) erase the guidelines OpenFlow from the particular information plane switches, in this manner upsetting the passage.

Code structure of RAN simulator:

                                              

   

Controller:

The controller code contains 3 floodlight modules 

• MME is the floodlight module which is in charge of associating with the RAN test system by means of the default switch. It contains different cases relying upon the sort of message got from RAN and a relating activity. It delegates different occasions to SGW.java and is in charge of introducing/uninstalling rules into the default switch. In addition, it additionally in charge of speaking with HSS.
• SGW.java plays out the control plane functionalities of SGW including introducing/uninstalling OpenFlow rules into the SGW switch. It additionally goes about as an interface amongst MME and PGW.

• PGW.java plays out the control plane functionalities of PGW including introducing/uninstalling OpenFlow rules into the PGW switch.