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IETF SRv6

Internet Engineering Task Force (IETF) SRv6 (Segment Routing over IPv6) is a network routing architecture and protocol mechanism (network routing) defined within the IETF that encodes segment routing instructions as IPv6 addresses and headers to steer traffic through an IPv6 network.

  • Encodes a list of routing segments in IPv6 headers to control packet paths (network routing).
  • Implements segment routing data-plane behavior directly over native IPv6 without Multiprotocol Label Switching (MPLS) (network routing).
  • Supports Traffic Engineering (TE) and service chaining by steering flows through specific network functions and nodes (traffic engineering).
  • Aligns with IETF segment routing architecture and IPv6 standards for interoperable deployment across IP networks (network protocol standardization).
  • Targets use in large-scale service provider, data center, and enterprise backbones requiring explicit path control and policy-based forwarding (network infrastructure).

More About IETF SRv6

IETF SRv6 (Segment Routing over IPv6) operates as a segment routing data plane over IPv6 (network routing), encoding path and service instructions directly into IPv6 packet headers. It extends IPv6 to carry a list of segments, each represented as an IPv6 address or instruction, enabling explicit steering of packets through a defined sequence of nodes, links, or functions without per-flow state in the core of the network.

The core purpose of SRv6 is to provide path control, policy-based routing, and service chaining capabilities (traffic engineering) using only IPv6 mechanisms. Instead of relying on MPLS labels, SRv6 uses IPv6 addresses and an SRv6 Segment Routing Header (SRH) (network protocol extension) to describe the sequence of segments. Each segment can represent a topological instruction such as “forward via this node” or a service instruction such as “process at this function,” which allows operators to define flexible forwarding behaviors.

Within the broader IETF segment routing framework (network architecture), SRv6 is the IPv6-based instantiation of segment routing, complementing MPLS-based segment routing while using the globally standardized IPv6 protocol as its foundation. The IETF documents SRv6 behavior, segment formats, and associated control-plane interactions through Internet-Drafts and RFCs (standards development), specifying how routers interpret and act on SRv6 segments and headers.

Enterprises and service providers can use SRv6 to implement TE policies (traffic engineering), steering certain applications or tenants along specific paths that meet latency, bandwidth, or security requirements. SRv6 can also support VPN-style services, network slicing constructs, and chaining of virtualized or physical network functions (network services), all encoded as sequences of IPv6 segments. Because the forwarding behavior resides in headers carried by each packet, intermediate nodes do not require per-flow state, which can simplify core network design.

SRv6 integrates with existing IPv6 routing protocols such as IS-IS and Open Shortest Path First (OSPF) for segment distribution (routing control plane), as documented in IETF work, and can coexist with traditional IP and MPLS deployments. This alignment with standardized IPv6 and IETF routing protocols supports multi-vendor interoperability (interoperability) when implementations follow the same SRv6 specifications.

For enterprise technical stakeholders, SRv6 is relevant as a network architecture and protocol option (network architecture) for IPv6-based backbones, data center fabrics, and WANs that require explicit path control, service chaining, and simplified core operations. In a technical directory or taxonomy, IETF SRv6 fits under IETF network protocol standards, with subcategories of IPv6 extensions, segment routing, TE, and service chaining mechanisms.

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