Diameter Protocol Simulator Enhanced to Support Gy and Ro Interfaces

Welcome to another October 2015 issue of GL Communications' Newsletter providing information and insight into our enhanced MAPS™ Diameter Protocol Emulator - Scripted LTE Diameter S6a, S6d, Cx/Dx, Gx, Rx, Gy/Ro Interfaces Emulation.

Overview

The Diameter protocol is intended to provide a framework for Authentication, Authorization and Accounting (AAA) for applications such as network access, roaming, and IP mobility. The AAA protocols are used to determine whether the user is allowed to connect to the network (Authentication) and use a particular service (Authorization). It is also used to track network resources used by end-user for accurate billing (Accounting).

AAA protocols such as TACACS and RADIUS were initially deployed to provide dial-up PPP and terminal server access. Over time, with the growth of the Internet and the introduction of new access technologies, including wireless, DSL, Mobile IP and Ethernet, routers and network access servers (NAS) have increased in complexity and density, putting new demands on AAA protocols. As a result, the Diameter protocol has been chosen as the AAA protocol in all next generation fixed and mobile IP- based networks (IMS, LTE). The Diameter protocol is a considerably more sophisticated protocol for mobility management, policy and charging (online and offline) control. It is designed to support data, services, and applications with extreme flexibility and is expected to replace all legacy protocols such as MAP, LDAP, Radius, and others.

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Functional Procedure

Within LTE-IMS network, MAPS™ Diameter can simulate S6a, S6d, Cx/Dx, Gx, and Rx Interfaces  to test LTE-IMS network elements such as the MME (Mobility Management Entity), HSS (Home Subscriber Server), CSCF (Call Session Control Function), SGSN (Serving GPRS Support Node), PDN GW (Packet Data Network Gateway), AF (Application Function) , PCRF (Policy and Charging Rules Function),CTF (Charging trigger Function) and OCS (Online Charging System).Recently MAPS™ Diameter has been enhanced to support simulation of Gy and Ro interfaces in addition to existing interfaces. The simulation of other interfaces (Rf, Dh, Gq, Zh, Zn, Wa, Wd, Wx, Wm, Wg, Pr) and elements will also be supported in near future.

The MAPS™ Diameter gives the users the unlimited ability to edit signaling messages to support various procedures listed below. MAPS™ Diameter supports both SCTP (Stream Control Transmission) and TCP (Transmission Control Protocol) transport protocol layers for PSTN signaling messages over IP networks.

MAPS™ Diameter also supports an End-to-End 4G LTE Communications Network Lab with all components to simulate both E-UTRAN and EPC (Evolved Packet Core), allowing complete testing of the LTE-IMS network.

Diameter over SCTP/TCP Protocol Stack	Supported Protocols	Standard / Specification Used
	Diameter	IETF RFC 3588 S6a & S6d - 3GPP TS 29.272 V10.3.0 Rx - 3GGP TS 29214-b10 Cx/Dx - 3GPP TS 29.228 & TS29.229 Gx - 3GPP TS 29.212 & TS 23.203  Gy/Ro (DCCA)- 3GGP TS 32.225 , 3GPP TS 32.299 and IETF RFC 4006
	SCTP	RFC 4960
	TCP	RFC 793

S6a interface procedures		Location Management, Subscriber Data Handling, Authentication, Fault Recovery, and Notification
Rx interface procedures		AA-Request/Answer, Re-Auth-Request/Answer, Abort-Session-Request/Answer, and Session-Termination-Request/Answer
Gx interface procedures		IPCAN Session Establishment and Modification
S13 interface procedures		ME (Mobile Equipment) Identity Check procedure
Sh interface procedures		User data handling procedures (User-Data-Update, Subscriber-Notification, User-Data-Pull)
Gy/Ro interface procedures		Immediate Event Charging (IEC), Event Charging with Unit Reservation (ECUR), Session Charging with Unit Reservation (SCUR)  CC-Request/Answer, Re-Auth-Request/Answer Procedures

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Testing CTF and OCS entities in Gy/Ro interface

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MAPS™ configured as CTF in GY/RO interface (Session Based Charging)

Session Based Charging is a credit-control (CC) process that makes use of several interrogations: the first (INITIAL_REQUEST), a possible intermediate (UPDATE_REQUEST), and the final (TERMINATION_REQUEST). The first interrogation is used to reserve money from the user’s account and to initiate the process. The intermediate interrogations may be needed to request new quota while the service is being rendered. The final interrogation is used to exit the process.

The MAPS™ Diameter as CTF initiates a call by sending a CCR (Credit Control Request) message to the test the OCS. The CCA (Credit Control Answer) response message received back from the DUT (OCS) can be verified as shown in the message sequence window below.

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MAPS™ configured as OCS in GY/Ro interface (Event Based Charging)

Event Based Charging is aone-time event charging process used when there is no need to maintain any state in the Diameter credit-control server; for example, enquiring about the price of the service, balance check, direct debiting, and refund. The use of a one-time event implies that the user has been authenticated and authorized beforehand.

In CTF testing, MAPS™ Diameter is loaded with a set of inbuilt scripts to handle the incoming messages. MAPS™ Diameter acts as OCS and sends response to the one-time event based charging request as shown in the message sequence window below.

For comprehensive information on the application, please visit MAPS™ Diameter Protocol Emulator web page.

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