Overview of Segment Routing IPv6
Definition
Segment Routing IPv6 (SRv6) is a protocol designed to forward IPv6 data packets on a network based on source routes. IPv6 forwarding plane-based SRv6 enables the ingress to add a segment routing header (SRH) into IPv6 packets. An explicit IPv6 address stack is pushed into the SRH. Transit nodes continue to update IPv6 destination IP addresses and offset the address stack to implement per-hop forwarding.
Purpose
Future networks will be 5G oriented. Bearer networks also need to be adapted to this and face the trends in simplifying networks, providing low latency, and implementing software-defined networking (SDN) and network functions virtualization (NFV).
To develop 5G networks, customers hope to use IPv6 addresses to more easily impalement VPNs. The SRv6 technique uses the existing IPv6 forwarding techniques and extends the IPv6 header to implement label forwarding-like processing. Some IPv6 addresses are defined as instantiated segment IDs (SIDs). Each SID has its own explicit functions. SIDs are operated to implement simplified VPNs and flexibly plan paths.
Benefits
Streamlines network configurations to more easier to implement VPNs.
SRv6 does not use MPLS techniques and is fully compatible with existing IPv6 networks. Nodes merely support IPv6 forwarding, not MPLS forwarding. Transit nodes can be incapable of SRv6 and forward IPv6 packets carrying the SRH over routes.
Facilitates traffic optimization on IPv6 forwarding paths.
SIDs with various service types are used to flexible plan explicit paths on the ingress to adjust service traffic.
