G-SRv6

What Is G-SRv6?

Generalized Segment Routing over IPv6 (G-SRv6) is an extension of SRv6 that introduces Generalized SIDs (G-SIDs) supporting multiple SID lengths. G-SRv6 achieves significant reduction in segment list (SID list) overhead, by encoding G-SIDs using compression techniques. This reduction results in decreased SRv6 header overhead. Moreover, G-SRv6 enables hybrid programming with both 128-bit SRv6 SIDs and compressed SIDs, allowing for incremental upgrades in a network. With G-SRv6, network operators can smoothly transition from SRv6 to G-SRv6 by upgrading only specific nodes as needed, ensuring a seamless upgrade and evolution process.

Advantages of G-SRv6

G-SRv6, as an evolution solution compatible with SRv6, serves as a more efficient SRv6 technology, playing a crucial role in promoting the deployment of SRv6. G-SRv6 provides the following advantages:

• Enhanced Transmission Efficiency. G-SRv6 utilizes 32-bit compressed SIDs to reduce segment list overhead, leading to a significant improvement in network transmission efficiency.

• Improved Forwarding Performance. In SRv6 forwarding, the primary action is to read the active SID pointed to by the Segments Left field and copy it to the Destination Address (DA) field in the IPv6 header. With G-SRv6, the shortened segment list reduces the SID stack depth, making it easier for hardware to read SIDs and eliminating the need for a second read. G-SRv6's lower hardware requirements enable some legacy devices in existing networks to support it through software upgrades, avoiding the costs of hardware upgrades and facilitating network upgrades.

• Mitigated MTU Exceedance Risk. In G-SRv6 scenarios, one to three 32-bit compressed SIDs may be added for TI-LFA protection. This added length is significantly shorter than in SRv6 scenarios, substantially reducing the risk of exceeding the MTU.

Applications of G-SRv6

• The current cloudification of existing IP RAN enterprise services and 5G 2B FMC private line services primarily focuses on existing IP RANs. These networks often contain legacy devices that may struggle to handle a deep SRv6 SID stack efficiently. To address this issue, G-SRv6 can reduce the SRv6 SID stack depth, which in turn reduces the hardware requirements for devices and facilitates a smooth network evolution.

• Additionally, for slice-based cloud private networks, the minimum slice granularity currently stands at 100 Mbps and is expected to decrease further. G-SRv6 can help minimize packet header overhead and improve packet transmission efficiency, ultimately helping users reduce associated fees.

• Metro networks primarily provide fixed broadband cloudification acceleration services for public, education, government, and enterprise users. These services have stringent latency requirements that affect both network transmission and device processing. To meet these requirements, network slicing technology can reserve resources to ensure that network transmission latency stays below the specified threshold. Furthermore, G-SRv6 can enhance packet forwarding performance and reduce device processing latency.