ETSI publishes new spec and reports on 5G tech

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.

Conquering video: overcoming the congestion conundrum periodically invites third parties to share their views on the industry’s most pressing issues. In this piece Raffaele D’Albenzio, Solution Architect at F5 Networks, looks at ways CSPs can counter the challenges posed by increased video consumption in a cost-effective way.

Video is fast emerging as the Holy Grail for mobile operators and the numbers don’t lie. Facebook users consume eight billion videos a day and 82% of those active on Twitter view video content. Significantly, 90% of Twitter video views and 60% of YouTube views are now from users on mobile devices.

The video bonanza is partly fuelled across the industry by ambitious service providers offering zero rating approaches or aggressively priced unlimited data plans. For example, mobile network Three announced in July plans to include unlimited video streaming for free as part of some contracts. This has been further complicated by ethical debates about the management of network traffic by major operators, as regulators seek to uphold net neutrality. In this context, intelligent traffic management is key for mobile network operators adapting to a landscape with no scope to relax customer service standards.

The majority of mobile video has two main characteristics: encryption via SSL (or similar protocols) and the fact that it is based on Adaptive Bit Rate (ABR) technology, which changes video resolution depending on available bandwidth. Although encryption is a key security feature, it can hinder the ability of operators to maintain a high-quality user experience, as the encryption protocols used by video providers such as Netflix and YouTube can prevent data optimisation using standard traffic management tools. To counter the challenges posed by increased video consumption in a cost-effective way, service providers must look to improve the way Transmission Control Protocol (TCP) works on the mobile network.

TCP is the key transport protocol of internet infrastructure; the glue which, together with Internet Protocol (IP), ensures that all applications connect smoothly to our devices. It allows us to share resources with billions of people all over the world at the same time. It also establishes and manages traffic connections and congestion while taking care of transmission errors.

Today, the ability to detect video streams and manage them using TCP-Proxy-based bandwidth controls or Shaping Capabilities for User Datagram Protocol-based video streams can have a profound impact. It enables service providers to adapt and reduce the amount of bandwidth used by video streams, while continually safeguarding the user experience. Looking ahead, TCP optimisation will become increasingly important to service providers by significantly improving download performance by signal strength on faraway networks

Furthermore, TCP optimisation also allows mobile operators access to radio-centric congestion control algorithms, that adapt to the idiosyncrasies of specific networks. These algorithms are vital conduits to improve traffic flow and the overall user experience. Techniques such as these can also decrease the time between client and TCP termination, enabling both sides to react quickly in the instance of isolated losses or congestion events in the network. Furthermore, it is possible to decrease retransmissions to improve radio resource efficiency.

TCP has many moving parts, with new ones being added every day. Making sense of it all without proper fine-tuning is ill-advised. It is crucial for decision-makers to choose a TCP stack that encompasses high goodput and minimal buffer bloat, as well as allowing for fairness between flows. In the era of mass video dissemination and usage, the TCP must be more than a static bolt-on. Integration with other functionalities — including deep packet inspection, traffic steering, and load balancing — is essential.


Raffaele low-resRaffaele D’Albenzio is a Solution Architect at F5 Networks. He specialises in IP networking and network security, with over 15 years of experience in the enterprise tech and service provider markets.