Segment Routing IPv6 (SRv6) is a next-generation IP bearer protocol that combines Segment Routing (SR) and IPv6. Utilizing existing IPv6 forwarding technology, SRv6 implements network programming through flexible IPv6 extension headers.
SRv6 reduces the number of required protocol types, offers great extensibility and programmability, and meets the diversified requirements of more new services. It also provides high reliability and offers exciting cloud service application potential.
Why Do We Need SRv6?
Challenges Facing Traditional Networks
The advancement of global informatization is accelerating the development of Internet applications. As networks grow in scale and we embrace the cloud era, we see more diversity in the types of network services and the requirements they pose on the networks. In this context, traditional IP/MPLS networks are presented with a series of challenges:
Isolated IP bearer network islands: Although MPLS unified bearer network technologies, the IP backbone, metro, and mobile bearer networks are independent MPLS domains that are separated from each other. Consequently, they must be interconnected using complex technologies, such as inter-AS VPN, leading to more complex E2E service deployment. In addition, when L2VPN and L3VPN services coexist, numerous protocols (such as LDP, RSVP, IGP, and BGP) may coexist on a device, further complicating management and resulting in difficult large-scale service deployment.
Limited programming space in IPv4 and MPLS: Many of today's new services require additional forwarding information to be added to packets. However, the IETF has announced that it will no longer formulate new standards for IPv4. In addition, as the MPLS label space is fixed at 20-bit long and lacks extensibility, it can no longer sufficiently meet the requirements of new services for network programming.
Decoupling of applications and bearer networks: Decoupling makes it difficult to optimize networks and improve their value. As a result, many carriers find themselves stuck as a provider of pipes, unable to benefit from value-added applications. Moreover, the lack of application information means that carriers can only implement network adjustment and optimization in a coarse-granularity way, leading to wasted resources. Throughout the years, attempts have been made to move MPLS closer to user hosts and applications, but all have failed due to a variety of reasons, such as too many network borders and complex management.
Tight coupling of the data and control planes: These planes are bound together for sale and evolution, prolonging service provisioning and making it difficult to cope with the rapid development of new services.
SRv6 resolves the preceding problems and transports networks into a new era.
Technical Value of SRv6
Intelligence
SRv6 offers powerful programming capabilities. With three-dimensional programming space — namely, network path, service, and forwarding behavior — SRv6 meets the diverse requirements of numerous services, making it ideal for service-driven networks.
Totally based on the SDN architecture, SRv6 bridges the gap between applications and networks. By delivering application information to networks, SRv6 enables network scheduling and optimization based on global information.
Ultra-simplified
With SRv6, LDP or RSVP-TE is no longer required — and neither are MPLS labels. This greatly simplifies protocols and management. In addition, the combination of EVPN with SRv6 replaces many protocols, greatly simplifying IP bearer networks.
Simplifying network protocolsSRv6 overcomes MPLS inter-domain boundaries, is easy to deploy, and improves the inter-domain deployment experience.
Native IP
SRv6 forwards packets based on native IPv6 and is implemented by extending the packet headers without changing the original IPv6 packet encapsulation structure. As SRv6 packets remain IPv6 packets, they can still be identified by common IPv6 devices. This means that SRv6 devices can be deployed in conjunction with common IPv6 devices. Due to SRv6's better compatibility with existing networks, it enables fast service rollout and smooth evolution. In addition, the native IPv6 feature of SRv6 enables it to be deployed in data center networks or even on user terminals, promoting cloud-network convergence.
Thanks to the above characteristics, SRv6 is ideally suited for building intelligent IP networks. It also introduces IPv6 development opportunities, ushering in a new era of IPv6+.
For more information, see SRv6
