Diameter Protocol in 4G LTE

What is Diameter in LTE?

Diameter is an AAA (Authorization, Authentication and Accounting ) protocol which works at the application layer in OSI model over TCP/SCTP or TLS/DTLS (for security) protocol. Diameter is the successor of RADIUS (Remote Remote Authentication Dial In User Service) protocol that runs over UDP.

This AAA technology is a message based protocol, where AAA nodes exchange messages and receive Positive or Negative acknowledgment for each message exchanged between nodes. For message exchange it internally uses the TCP and SCTP which makes diameter reliable. Its technical specifications are given in RFC-6733 Diameter Base Protocol. (Please refer to this link to RFC-6733 for the original definition)

Advantages of Diameter compared to Radius

This AAA technology has following improvements over RADIUS:   

a) More Reliable
b) Transport Layer Security                   
c) Fail-over Mechanism
d) Server Initiated Messages
e) Agent Support
f) Audit-ability
g) Transition Support
h) Capability Negotiation
i) Roaming Support
j) Peer Discovery & Configuration

Defaults Ports                      

The default port is 3868 for TCP/SCTP and 5868 for TLS/DTLS.

More details on AAA in LTE

LTE Evolved Packet Core (EPC) generally have 5 nodes:

1) Mobility Management Entity (MME)
2) Home Subscriber Server (HSS)
3) Serving Gateway (S-GW)
4) PDN Gateway (P-GW)
5) Policy and Charging control entity/Function (PCRF)

These nodes interact then uses diameter based interfaces. Please see the diagram below for more detailed information on this topic:

Diameter Protocol in LTE

The Dark Lines in the diagram show the major Interfaces in the LTE EPC (Evolved Packet Core). Sometimes the CSS data is not stored at HSS then S7a interface is used to communicate with the MME. S7a is also a diameter based interface.

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Our team of experts has a wealth of experience and knowledge of designing, dimensioning, implementing and supporting Private LTE 4G & 5G networks for a diverse range of applications. Please feel welcome to contact us.
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Build Private LTE 4G & 5G Networks

Private LTE brings major benefits compared to Public LTE networks. A Private LTE network connects people/things belonging to an enterprise (normally across a campus or site), and where data needs to be kept totally secure by avoiding transmitting it through the core network of a mobile operator.  Full private ownership of the whole LTE network – including Base Stations and Core – has several advantages.

Major Benefits of Private LTE

CableFree LTE Base Station
A typical 4G LTE Base Station

The many benefits of a Private LTE network can include:

  • Guaranteeing coverage and capacity in the target coverage area. Organisations can design, engineer and update the RAN to meet their specific performance demands, including for coverage, configuring uplink and downlink, set usage policy, determine which users connect, how traffic is prioritised, and other key parameters.
  • Optimising parameters in the LTE radio to operate in challenging physical environments (e.g., warehouse or oil/gas facility with lots of metal). This can include fast recovery from failure, or optimizations for reliability, and for latency. This is not possible when connecting to a public network, where such parameters are under control of the operator, not the user.
  • Retaining control of critical data: In private networks, the organization controls its own security and can ensure that sensitive information does not leave the network; this is an essential requirement for many types of businesses and security-focused organisations. Another benefit of keeping data and the core network on the private LTE network is the risk of service disruption due to a WAN link outage is eliminated.
  • Dedicated coverage and capacity of high speed 4G network with the ability to customise performance to enterprise needs
  • High speed, high capacity, reliable and secure mobile broadband communication layer for mission-critical and business-critical people, machines and applications
  • A fast route to digital transformation and IoT, bringing intelligent insights for more efficient operation, agility, quality and innovation
  • LTE mobility – the use of advanced applications on mobile platforms (vehicles, robots, etc) and transparent hand-over to public LTE networks outside of private LTE network coverage
  • In mining and minerals, private LTE can be used to automate remote facilities and enhance security
  • Enabling IoT applications which can run over a Private LTE network

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