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ПРЕДСТАВЛЕНИЕ НАУЧНОЙ РАБОТЫ
ВЕСТНИК НАУКИ IMPLEMENTATION OF THE DIAMETER PROTOCOL IN THE MOBILE 4TH GENERATION (4G) RADIOTELEPHONE NETWORK
^И ТВОРЧЕСТВА Aghayeva A.A,
Azerbaijan State Oil and Industry University, Baku, Azerbaijan
E-mail: aytacagayeva18@gmail.com
Abstract. Mobile 4G networks are becoming more and more popular everywhere since they offer subscribers higher quality connection and data transmission security. The DIAMETER protocol is essential for providing end-to-end security for Authentication, Authorization, and Accounting (AAA) services in the Next Generation Mobile Network Architecture. In the LTE network design, the DIAMETER protocol is used to provide AAA services, greater data rates and increased bandwidth in the network for mobility management during roaming scenarios. This paper provides explain what Diameter is, how it works closely with the Mobile IP protocol, and some further applications.
Key words: Diameter protocol, 4g network, IMS, LTE.
Introduction
In IP Multimedia Subsystem (IMS)-based networks Diameter is the de facto AAA protocol. Diameter is a signaling protocol used in telecommunications networks for the transmission of service data. It's also the foundation of the core EPS (Evolved Pack System) network and LTE (Long Term Evolution) technology. Besides supporting AAA services in LTE and 4G networks, Diameter also supports stream control transmission protocol (SCTP) and transmission control protocol (TCP). Both SCTP and TCP on port 3868 are used by Diameter, which offers dependable transport for proper communication with Diameter nodes through the exchange of diameter specific messages. The Diameter node responds positively or negatively to each message it receives from a peer. The base protocol specifies message format, transport, error reporting and security services that must be utilized by all Diameter applications and supported by all Diameter implementations. These rules are applicable to all message exchanges between Diameter nodes. The Diameter base protocol is concerned with capability negotiation, sending of messages and the eventual abandonment of peers.
The Diameter Protocol is used by a number of LTE and IMS network operations, including the ones listed below:
ВЕСТНИК НАУКИ И ТВОРЧЕСТВА
DEA (Diameter Edge Agent) is a border agent. It serves as a proxy agent for signaling traffic from networks of other operators and often runs at the edge of an operator's signaling network.
DRA (Diameter Routing Agent) is a routing agent which carries out routing of Diameter-traffic.
HSS (Home Subscriber Server) is a subscriber data server. One of the most crucial components in the infrastructure of the 4G network of the LTE standard. It serves to store important user information and information about the subscribers' actions.
IMSI (International Mobile Subscriber Identity) is an international mobile network subscriber identifier. Serves to globally identify each cell phone subscriber in a unique way.
MME (Mobility Management Entity) is a mobility management node. MME selects a serving gateway and offers the ability to switch between base stations, operate in roaming, authenticate user devices by communicating with the HSS.
SS7 (Signaling System 7) is a common channel signaling system used in international and local telephone networks around the world.
How does the diameter protocol work?
The node running the Diameter protocol can either be a client or a server, depending on the network architecture. The Diameter client will be the Diameter node that receives the user connection request. The client node will send an access request message to another Diameter node following the collection of user credentials (username and password). Based on the data supplied, this Diameter server node authenticates the user. The user will receive an access response via the relevant Diameter client node if the information is approved. If rejected, the user will see a message saying that access is denied. By monitoring the use of services and resources, Diameter Protocol also advances the security of the Domain Name System (DNS). In cloud environments, AAA services are critical to provide seamless support for multinational subscriber communities.
Diameter agents
Each of the agents in Diameter has a distinct role that is defined. The agents in Diameter are as follows.
Diameter Relay Agent: Message routing is controlled by Diameter relay agents based on destination data. A relay agent doesn't handle any processing at the application level. The only thing changed is route information. It controls the transaction state rather than the session state.
Diameter Proxy Agent: Based on the Diameter routing table Proxy agent routes the Diameter messages. It has the ability to alter messages, control transaction state, and implement policy enforcement function. The session state may also be managed by it. Diameter Routing Agent is an example of Diameter Proxy Agent in LTE.
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ВЕСТНИК НАУКИ И ТВОРЧЕСТВА
Diameter Redirect Agent: Redirect Agent only returns response with crucial information for direct communication with the destination. There is no management of session or transition states. Redirect Agent just offers relaying services to all Diameter apps; it doesn't carry out any processing at the application level. The SLF (Subscriber Locator Function) in IMS is one example.
Translator: Translator is responsible for translating messages from one protocol to another. Internet service providers can integrate user databases from various domains with the use of this agent.
Development of diameter base protocol
A peer-to-peer protocol called Diameter includes sending attribute-value pairs (AVPs). A header and one or more AVPs are both parts of a Diameter message. The type of Diameter application determines the collection of AVPs in each message, and the Diameter protocol also supports extension by introducing additional commands and AVPs. Diameter establishes guidelines for conducting sessions and performing accounting tasks and allows numerous peers to discuss their capabilities with one another. Accounting applications can use the standard Diameter protocol by itself, but it is always enhanced for a specific application when it comes to authentication and authorization. The accounting functionality of the basic protocol must be supported by Diameter nodes (clients, servers, and agents). Furthermore, they must completely support every Diameter application required for the implementation of the nodes service. Sending a message to another Diameter peer initiates communication between Diameter peers. A specific Diameter application decides which set of AVPs to include in the message. The Session-Id is one AVP that is used to identify a user's session. The Session-Id is part of the initial request for a user's authentication and/or permission. The user's session is then identified in all ensuing communications by the Session-Id. By returning an answer message with the Result-Code AVP set to indicate an error occurred, the communicating party can accept or reject the request. Depending on the Diameter application being used, a request will result in a specific response from a server or client. Upon receipt of the Session Termination-Request, Session-Termination-Answer, the passing of the allowable service time in the Session-Timeout AVP, and in accordance with the guidelines defined in a specific Diameter application, the session state (associated with a Session-Id) must be released.
Implementation
The DIAMETER protocol is an operational solution that has been applied in LTE/4G networks, situated at a layer above SCTP/TCP.
Fig. 1 Features provided by DIAMETER
The functionality offered by the DIAMETER protocol is depicted in Figure 1. In the LTE architecture, the Home Network, which is the 4G network, utilizes the DIAMETER protocol to facilitate communication between various entities.
Fig. 2 Implementation of DIAMETER
Figure 2 illustrates the deployment of the DIAMETER protocol, which is situated between the application interface and other DIAMETER peers to offer AAA services. Additionally, the monitoring process preserves the messages in a queue for future processing, which forms a part of the DIAMETER protocol.
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Fig. 3 Basic LOCAL call flow diagram
Figure 3 demonstrates the fundamental LOCAL call flow diagram that depicts the mapping of the Gx interface elements (IEs) onto attribute value pairs (AVPs).
Conclusion
This study highlights how the DIAMETER protocol enables high data rates and throughput for both service and control planes. The IMS architecture has various reference points that allow for the transmission of user credentials, accounting data, and roaming information in both planes. The s6a, Gx, and Gy interfaces in the IMS architecture use Diameter for subscription, client intent notification, and attribute definition. The performance test results reveal that Diameter can efficiently manage heavy message traffic, optimize memory usage, and provide AAA services to all diameter nodes.
References:
1. "Role of Diameter in LTE Roaming and Interoperability" White paper, Intellinet Technologies India Pvt Ltd, Florida, GSMA 2013.
2. "Diameter Request for comments 6733" (RFC6733). URL: https://www.rfc-editor.org/rfc/rfc6733
3. GPP Technical Specification TS 32.299, "Online charging server" (Release 10.5). URL: https://www.3gpp.org/
4. "Diameter Network Signaling in 4G LTE Networks: Architecture, Protocols, and Services" by Ravi Kumar, 2019.
5. "Diameter Network Signaling in 4G LTE Networks: Architecture, Protocols, and Services" by Ravi Kumar, 2019.
6. "Diameter Protocol: Concepts and Design Principles for Effective Communication" by Christophe Muller and Markus Mueck , 2018.
7. "Understanding LTE and its Performance" by R. Venkatesan , 2017.
8. "Practical Guide to LTE-A, VoLTE and IoT: Paving the Way Towards 5G" by R. Venkatesan, 2019.
