As the demand for 5G services continues to grow, Mobile Network Operators and Service Providers need solutions that simplify the deployment and delivery of their services. One solution gaining momentum is 5G with Segment Routing v6 Mobile User Plane (SRv6 MUP).
SRv6 MUP is a new routing technology designed to streamline the deployment and delivery of 5G services by providing a simplified and segment-based approach. This article provides an overview of SRv6 MUP, its underlying SRv6 technology and its benefits for next-generation mobile networks.
What is SRv6?
SRv6 is an innovative routing technology based on the IPv6 protocol, developed by the Internet Engineering Task Force (IETF) to improve the scalability and flexibility of IP networks. It simplifies the control plane by eliminating the need for MPLS tunneling protocols such as LDP and RSVP-TE. It uses information in the IPv6 header for packet forwarding, rather than an MPLS label on the data plane. By unifying the transport on both the control plane and the data plane, SRv6 greatly simplifies network protocols, reduces operational complexity and maintenance, and enables end-to-end programmable network solutions.
Segment Routing inserts a segment list into each packet, either by the packet source or an intermediate network node. The segment list steers the packet through the network, based on the SR policy. As the packet passes through each SR node, the node uses the segment list to determine the next hop and the processing actions.
In SRv6, the key element to insert a segment list is the use of a Segment Routing Header (SRH) in the IP packet header. SRH is lightweight, and it carries the multiple instructions that egress and intermediate routers/nodes can execute a given instruction based on Segment Identifier (SID). Its use of a SID, makes SRv6 simpler than traditional transport networks. The SID is a short value that identifies a specific segment within the network that can be used to create custom network programming instruction types. By programming and managing these services in a more deterministic and granular way, SRv6 enables greater network customization, allowing service providers to tailor their offerings to the specific needs of their customers. This enhanced flexibility and programmability also makes it possible to create new and innovative services that were not previously possible with traditional networking technologies
SRv6 is a key enabler for 5G and IoT, as it provides more efficient use of resources, improved network reliability and better network management capabilities. Several leading Mobile Network Operators and Service Providers, like SoftBank, Iliad, and China Mobile use SRv6 in their mobile networks.
In addition, SRv6 enables the creation of a new generation of network services that provide greater flexibility and customization than traditional services. With SRv6, service providers can support a wide range of Layer 2 and Layer 3 services, such as virtual private networks (VPNs), Ethernet VPNs, service function chaining (SFC), and network slicing.
SRv6 Mobile User Plane
Mobile User Plane (MUP) is becoming an important component of 5G / Next Generation networks for the delivery of data services to end users. SRv6 is particularly well-suited to simplify the delivery of 5G services with MUP. SoftBank, a leading telecommunications and IT company based in Japan, pioneered the introduction of the SRv6 MUP solution with Arrcus, to bridge the gap between Mobile and IP/cloud-native technologies.
With exponential traffic growth in modern mobile networks, 5G must support a highly capable User Plane that allows operators to deliver 5G services economically, flexibly, and fast to market.
In User Plane, especially when a mobile user is anchored to multiple User Plane Functions (UPFs) in the network, is a difficult problem to solve and scale to meet 5G’s demands. SRv6 MUP elegantly combines IETF domain (SRv6) and 3GPP standards to solve these, and other complex issues. Because SRv6 MUP is based upon the IPv6 protocol, it can run over any IPv6 or MPLS network. Furthermore, adopting SRv6 MUP doesn’t require changes to how 5G mobile networks are built, and by being standards-based, enables interoperability and avoids vendor lock-in.
SRv6 MUP Architecture
- MUP Controller (MUP-C) - is the control plane node in MUP architecture responsible for creating and managing the routes within the MUP enabled networks. It provides an interface to get session information from the 5G Core Control Plane and converts it into routing information for the data plane nodes, in the form of BGP routes.
- MUP Provider Edge (MUP-PE) – located at the edge of the Transport Network, it performs translation of IP and/or GTP-U traffic into SRv6 on the Radio Access side. On the DN/Internet side of the network, MUP-PE connects the Internet/Data Network with the SRv6-enabled transport network. Directed by the session-transformed routes from MUP Controller with auto-discovery for the remote PEs, it sends the traffic to the appropriate destination MUP-PE connected to the target Radio Access Network (RAN), where the destination mobile user (UE) is located. That destination MUP-PE connects RAN, which could consist of tens of thousands of sets of CU/DU, via N3 interface (GTP protocol) and interworks it towards the Transport Network.
Benefits of SRv6 MUP for Service Provider networks
Business benefits – several architectural improvements described below lead to two very important business benefits for operators. The lifetime cost of deployment of a 5G network, both capital and operational, is substantially lower because of the network with smarter packet forwarding. Also, the additional ease in programmability of the network leads to acceleration in deployment cycles of a host of new monetizable applications for operators.
Reduced network complexity - SRv6 MUP reduces the operational complexity of network configurations and makes it easier for network operators to manage their networks. SRv6 eliminates the need for protocols like MPLS, LDP and RSVP-TE for QoS/traffic engineering. It is also able to steer traffic from tunneling/VPN protocols like GTP-U to SRv6. The SRv6 MUP provides additional deployment flexibility, as the N3 (RAN) and N6 (Internet/DN) interfaces do not need to be co-located on the same node, as in a 5G Core’s UPF.
Improved support for 5G and IoT - Network operators are enabled to offer differentiated value services within their networks, to help improve network scalability and reduce latency. SRv6 MUP allows network operators to create custom paths for UEs per 5G network slicing basis in the Transport Network, which improves network performance by reducing congestion and latency. This is crucial for resource-constrained IoT devices, which benefit from low-latency communications.
Better support for Edge Computing - SRv6 MUP provides more efficient use of network resources, improving network reliability and reducing operational costs. It allows deployment of a unified ‘network fabric’ that facilitates a converged network for Multi-Access Edge Computing (MEC), which requires high-speed, low-latency communications. It allows operators to easily add mobile edge sites within the network, at scale, overcoming the disadvantages of using other edge site deployment methods. SRv6 MUP allows for multiple mechanisms to separate traffic via slicing, differentiated QoS paths, and traffic rerouting in case of node failures or network congestion.
End-to-end Network Slicing - SRv6 MUP allows for a vast address space, to facilitate network slicing at scale. It also simplifies the creation of end-to-end slicing in the mobile network, by associating corresponding slices in the RAN and 5G Core, with slices in the transport network. These end-to-end slices support different traffic characteristics like QoS, latency and route resiliency in case of failure or congestion. The solution in the transport network can be orchestrated and managed using typical routing functions like Flex Algorithm (Flex Algo).
High scalability - SRv6 MUP is designed to work with the IPv6 protocol, which is best suited for the necessary scale and performance of 5G networks. The User Plane is transformed from session-based (as in UPF) to routing-based. Other transport technologies like MPLS, were designed to work with IPv4, which has a limited label space and a limited address space and can't scale to support the massive number of devices and applications associated with 5G and IoT.
Conclusion
SRv6 MUP is an optimal solution for next-generation 5G deployments by providing a more simplified and efficient way to build high-capacity networks. SRv6 MUP enables operators to improve network scalability and reliability, reduce latency and congestion, and provide network flexibility. It is a plug-in, standards-based solution, fully interoperable with leading 5G Core and RAN vendors.
These characteristics are vital for 5G networks to allow network operators to better monetize and manage their network, by widening their service offerings at the Edge to support a wide range of applications and services.