The European Telecommunications Standards Institute, ETSI, has released new specifications on packet formatting and forwarding, as well as two reports on transport and network slicing respectively.
The new specification, called Flexilink, focusing on packet formats and forwarding mechanisms to allow core and access networks to support the new services proposed for 5G. The objective of the new specification is to achieve efficient deterministic packet forwarding in user plane for next generation protocols (NGP). In the conventional IP networks, built on the Internet Protocols defined in the 1980s, every packet carries all the information needed to route it to its destination. This is undergoing fundamental changes with new technologies like Software Defined Networking (SDN) and Control and User Plane Separation (CUPS), where most packets are part of a “flow” such as a TCP session or a video stream. As a result, there is increasingly a separation between the processes of deciding the route packets will follow and of forwarding the packets.
“Current IP protocols for core and access networks need to evolve and offer a much better service to mobile traffic than the current TCP/IP-based technology,” said John Grant, chairman of the ETSI Next Generation Protocol Industry Specification Group (ISG). “Our specifications offer solutions that are compatible with both IPv4 and IPv6, providing an upgrade path to the more efficient and responsive system that is needed to support 5G.”
The new specification defines two separate services, a “basic” service suitable for traditional statistically multiplexed packet data, and a “guaranteed” service providing the lowest possible latency for continuous media, such as audio, video, tactile internet, or vehicle position. It is worth noting that Flexilink only specifies user plane packet formats and routing mechanisms. Specifications for the control plane to manage flows have already been defined in an earlier NGP document “Packet Routing Technologies” published in 2017.
The report “Recommendation for New Transport Technologies” analyses the current transport technologies such as TCP and their limitations, whilst also providing high-level guidance on architectural features required in a transport technology to support the new applications proposed for 5G. The report also includes a framework where there is a clear separation between control and data planes. A proof-of-concept implementation was conducted to experiment the recommended technologies, and to demonstrate that each TCP session can obtain bandwidth guaranteed service or minimum latency guaranteed service. The report states:
“With traditional transport technology, for all TCP traffic passes through DIP router, each TCP session can only obtain a fraction of bandwidth. It is related to the total number of TCP sessions and the egress bandwidth (100 M).
“With new transport technology, new TCP session (DIP flows) could obtain its expected bandwidth or the minimum latency. And most [sic.] important thing is that the new service is not impacted by the state that router is congested, and this can prove that new service by new transport technology is guaranteed.”
Importantly, the PoC experiment showed that the current hardware technology is able to support the proposed new transport technology and provide satisfactory scalability and performance.
The report “E2E Network Slicing Reference Framework and Information Model” looks into the design principles behind network slicing. The topic of network slices encompasses the combination of virtualisation, cloud centric, and SDN technologies. But there is gap in normalized resource information flow over a plurality of provider administration planes (or domains). The report aims to “provide a simple manageable and operable network through a common interface while hiding infrastructure complexities. The present document defines how several of those technologies may be used in coordination to offer description and monitoring of services in a network slice.” It describes the high level functions and mechanisms for implementing network slicing, as well as addresses security considerations.