SRv6

What Is SRv6?

Segment Routing IPv6 (SRv6) is an advanced IP bearer protocol that merges Segment Routing (SR) with IPv6. By leveraging the current IPv6 forwarding technology, SRv6 enables network programming via adaptable IPv6 extension headers. This protocol streamlines the necessary protocol types, provides exceptional scalability and customization, and addresses the varied demands of emerging services. Additionally, SRv6 ensures robust reliability and presents compelling possibilities for cloud service applications.

Why Is SRv6 Necessary?

The rapid advancement of global informatization is driving the development of Internet applications. As networks expand and we transition into the cloud era, we encounter a greater variety of network services with diverse requirements. In this environment, traditional IP/MPLS networks face several challenges:

• Limited programming space in IPv4 and MPLS poses a challenge as many new services require additional forwarding information in packets. The IETF's decision to no longer create new standards for IPv4 further complicates this issue. Additionally, the fixed 20-bit length of the MPLS label space limits its extensibility, making it inadequate for meeting the network programming requirements of new services.

• The presence of isolated IP bearer network islands poses a challenge, despite MPLS's efforts to unify bearer network technologies. The IP backbone, metro, and mobile bearer networks operate as independent MPLS domains, separated from each other. As a result, complex technologies are required to interconnect them, leading to more complex end-to-end service deployment.

• The separation of applications and bearer networks creates challenges in optimizing networks and enhancing their value. This separation often leaves carriers trapped in the role of providing basic connectivity, without benefiting from value-added applications. Furthermore, the absence of detailed application information restricts carriers to making network adjustments and optimizations in a coarse-grained manner, resulting in inefficient resource utilization.

• The close integration of the data and control planes hinders service provisioning and adaptation to the rapid evolution of new services.

SRv6 streamlines the required protocol types, enhances extensibility and programmability, and propels networks into a new era by addressing the aforementioned challenges.

What Is SR?

Segment Routing (SR) is a packet forwarding mechanism that simplifies network paths by breaking them into segments. Each segment is identified by a unique identifier (SID) and represents a specific function or hop along the path. By inserting these segments into packets at the ingress of the path, routers along the path can forward packets based on the segment information, eliminating the need for complex routing protocols.

Segment Routing (SR) is a packet forwarding mechanism that simplifies network paths by breaking them into segments. Each segment is identified by a unique identifier (SID) and represents a specific function or hop along the path. By inserting these segments into packets at the ingress of the path, routers along the path can forward packets based on the segment information, eliminating the need for complex routing protocols.

SR was developed in response to the increasing complexity of traditional routing protocols and the need for more flexible and efficient network paths. It allows for the dynamic steering of traffic along any path, providing greater control and flexibility in network routing.

SR can be implemented using different forwarding planes, such as MPLS or IPv6. MPLS-based SR is known as Segment Routing MPLS (SR-MPLS), where segments are represented by MPLS labels. IPv6-based SR is known as SRv6, where segments are represented by IPv6 addresses.

Overall, SR simplifies network routing, improves network efficiency, and provides more flexibility and control over network paths, making it an important technology in modern networking.

SRv6's Technical Value

SRv6 represents a significant advancement in IP networking, leveraging the IPv6 forwarding plane. By integrating the best features of SR and the inherent flexibility of IPv6, SRv6 brings several key benefits:

• Enhanced Intelligence

SRv6 boasts robust programming capabilities, offering a three-dimensional programming space encompassing network paths, services, and forwarding behaviors. This flexibility allows SRv6 to meet the diverse demands of modern services, making it an ideal choice for service-centric networks.

Built on the foundation of SDN, SRv6 bridges the gap between applications and networks. By providing application information to the network, SRv6 enables intelligent network scheduling and optimization based on global insights.

• Simplified Operation

With SRv6, the need for protocols like LDP or RSVP-TE is eliminated, as are MPLS labels. This streamlines protocol implementations and network management. Additionally, the integration of EVPN with SRv6 replaces multiple protocols, greatly simplifying IP bearer networks.

SRv6 overcomes the challenges posed by MPLS inter-domain boundaries, offering easy deployment and improving the overall inter-domain deployment experience.

• Native IP Integration

SRv6 forwards packets based on native IPv6, achieved by extending packet headers without altering the original IPv6 packet encapsulation structure. Since SRv6 packets retain their IPv6 nature, they can be recognized and processed by standard IPv6 devices. This allows SRv6 devices to seamlessly coexist with common IPv6 devices. This compatibility enables rapid service deployment and smooth network evolution, making SRv6 well-suited for data center networks and user terminals, facilitating cloud-network convergence.

Thanks to these attributes, SRv6 is poised to revolutionize the creation of intelligent IP networks, offering new possibilities for IPv6 development and ushering in a new era of networking with IPv6+.