Through continuous breakthrough of information communication technologies represented by integrated circuits, computers, optical communication, and networks, TCP/IP-based Internet technology developed at a rapid pace in the second half of the twentieth century. The Internet has now penetrated all aspects of society and profoundly affected people’s lives.
Different services, such as cloud services, mobile transport, industrial Internet, Internet of Vehicles (IoV), telemedicine, and holographic communication, all pose requirements on network transport. Currently, cloud-network synergy and 5G transport are the services that have the most urgent and clear requirements on network transport.
Network Evolution Trend
Cloud-Network Synergy Requirements
With the development of cloud computing technologies and industries, an increasing number of services and amount of data are migrated to the cloud. In addition, a large number of IT infrastructure resources that provide computing and storage capabilities exist on the network. The intra-cloud network, inter-cloud network, and user cloud network of the cloud computing infrastructure can’t form an organic whole, and end-to-end resource management and control cannot be implemented. Moreover, fragmented clouds can’t serve users as a whole IT resource pool, resulting in difficult incorporation into the ICT infrastructure. For a cloud to work, the cloud must be accessible to users, the key to which lies in the conditions and capabilities of the network between the cloud and users. A network can’t provide the IT capabilities required by users if it is non-perceptible, unmanageable, uncontrollable, unable to ensure security, and unable to provide best-effort information transmission. Therefore, promoting the integration of the cloud and network, implementing on-demand allocation of IT resources, and ensuring that IT resources are fully utilized have become a trend.
5G Transport Requirements
5G is the starting point for people to shift their focus from personal entertainment to a fully connected society. 5G applications will further improve communication and provide a more real-world experience. Compared with traditional mobile communications systems, 5G needs to meet the ultra-high performance challenges in diversified application scenarios, which poses new requirements, such as low latency, high mobility, and numerous connections, on transport networks. Changes in the 5G RAN architecture (such as separation of active antenna units, centralized units, and distributed units) also pose requirements for low latency on transport networks.
Transport Network Requirements
In cloud-network synergy and 5G transport scenarios, the transport network must have more convenient service provisioning capabilities and more efficient network operating capabilities, as well as higher service quality. Therefore, transport networks must meet the following requirements:
Network planning capability: Scenario-specific bandwidth guarantee policies need to be formulated, with end-to-end latency as the triggering mechanism. Many accurate underlying network parameters are used as the basis for determining a transport layer policy. According to the requirements for reliable and unreliable transmission in common scenarios, the transport layer design needs to ensure that the bandwidth guarantee policy for the transport layer meets the requirements of upper-layer applications.
Management and control for numerous connections: With the expansion of network infrastructure, more people will access the Internet and enjoy the convenience of the Internet. The number of global smartphone subscribers is estimated to exceed 6 billion by 2025. Compared with the sharp increase in the number of physical communication devices and machines such as mobile phones and vehicles, global IoT connections are projected to exceed 27 billion by 2025. The number of communication connections will continue to grow rapidly, and we will enter the era of massive connections. The transport network needs to support access management, congestion control, query and retrieval, release and tear-down, and status management on massive numbers of connections.
Network and application status awareness: Network status awareness is the basis of network resource management and control. The network status needs to be monitored accurately and completely in real time, including the network availability, usage, throughput, link or Net Element (NE) congestion status, and actual transmission paths of flows. Based on the real-time, accurate, and complete network status data, the resource management and control system needs to make comprehensive and accurate management and control decisions, including appropriately scheduling and allocating compute, storage, and network resources and formulating security control policies to improve the overall network usage and user experience.
E2E service automation: The intra-cloud, inter-cloud, and cloud access networks face different challenges and use different technologies (for example, VXLAN for intra-cloud networks, MPLS for inter-cloud networks, and MPLS and IPsec for cloud access networks). During service deployment, segment-by-segment interconnection is required. IT resources distributed in different data centers cannot be scheduled centrally, increasing the difficulty of service automation. A technology that is compatible with and unifies live-network technologies is needed to shield technical differences between networks in order to meet the requirements for unified resource management and service provisioning in the cloud era.
IPv6+, IPv6 Enhanced Innovation Promoting the Development of Next-Generation IP Network
The right technology is always developed at the right time. IPv6+, technology based on Segment Routing over IPv6 (SRv6) is introduced to meet the requirements of the 5G and cloud era. After the native IP era (network reachability) and MPLS era (converged multi-service transport), the data communications network will pave the way for the IPv6+ era featuring automation, intelligence, and cloud-network synergy.
Segment Routing over IPv6
Segment Routing over IPv6 (SRv6) allocates a segment to each node or link. The ingress combines these segments into an ordered list and instructs packet forwarding according to the list.0 SRv6 uses IPv6 addresses as segment IDs (SIDs). Therefore, SRv6 can be seamlessly integrated with IPv6 networks. With SRv6 enabled on key nodes, IP networks support network programming, cross-domain deployment, Traffic Engineering (TE), and fast switching. In this way, SRv6 can be compatible with the overlay network (VXLAN), underlay network (MPLS), and other IP-based networks (IPsec and GRE).
SRv6 has the following advantages:
Simplified protocol: Unlike MPLS that requires LDP and RSVP-TE in addition to IGP, SRv6 almost only uses IGP, simplifying O&M.
High scalability: RSVP-TE is typically used to implement TE on the live network and is a soft state protocol. Each node on the network needs to detect the status of each path. The protocol cost is high, which limits the number of TE tunnels and increases the difficulty of deployment and maintenance. SRv6 path programming is performed on the ingress. The ingress only needs to combine the segments of a limited number of links and nodes even when a large number of paths exist.
Excellent programmability: SRv6 segments are similar to computer instructions. They are orchestrated to implement corresponding functions. SRv6 supports flexible establishment of paths to meet different requirements, ensure service latency, and optimize forwarding paths to guarantee SLAs, as well as programming of value-added services to release network values.
Reliable protection: SRv6 provides network-wide Fast Re-Route (FRR) protection, which resolves long-term technical problems on IP networks and provides complete FRR reliability protection while meeting network scalability requirements.
High compatibility to achieve end-to-end automation: SRv6 uses an IPv6-based addressing mode. It can be deployed on any reachable IPv6 network and be compatible with all IPv6 networks without compromising network capabilities. Conventionally, services were deployed segment by segment. SRv6 enables service deployment only on the ingress and egress, achieving service automation.
IPv6+, IPv6 Enhanced Innovation Promoting the Development for the Next-Generation IP Network
IPv6+, the IPv6 Enhanced Innovation represented by protocol innovation such as SRv6, BIERv6 (Bit Indexed Explicit Replication version 6), etc. , combined with AI such as network analysis, intelligent tuning, etc. is introduced to meet requirements, such as flexible networking, on-demand services, differentiated assurance, and network visualization, for 5G transport and cloud-network synergy. This technology system implements unified network deployment, flexible programming, and scalable expansion. It supports network visualization, application awareness, and scalable slicing, therefore IPv6+ is expected to promote the development for the Next-Generation IP Network.
Summary and Prospect
IPv6 is not the whole of the next-generation Internet, but the starting point and platform for innovation of the next-generation Internet. With the large-scale deployment of IPv6, IPv6+, the IPv6 Enhanced Innovation will be widely used on networks to form an automated and committed next-generation network similar to how MPLS formed an era, and promote the rapid development of 5G and cloud services.