Micro SIDs: A Solution for Efficient Representation of Segment IDs in SRv6 Networks

The Segment Routing (SR) architecture is based on source routing. Within an SR enabled network, a list of instructions called segments can be added to the packet headers to influence the forwarding and the processing of the packets. In SRv6 (Segment Routing over IPv6 data plane) the segments are represented with IPv6 addresses, which are 16 bytes long. There are some SRv6 service scenarios that may require to carry a large number of segments in the IPv6 packet headers. Reducing the size of these overheads is useful to minimize the impact on MTU (Maximum Transfer Unit) and to enable SRv6 on legacy hardware devices with limited processing capabilities that could suffer from the long headers. In this paper we present the Micro SID solution for the efficient representation of segment identifiers. The proposed Micro SID solution has been implemented on three different architectures (VPP, Linux, P4) and interoperability tests have been performed. We also analyze the reduction of the header size that can be achieved with Micro SIDs and compare it with other proposals for segment list compression. Our results show that the header size can be reduced up to 75%. Finally, we mention that a fundamental asset of the proposed Micro SID solution is the full compatibility and seamless interoperability with existing SRv6 architecture.