  Software-Defined Wide Area Networks (SD-WANs) are used to provide services to
enterprises with geographically dispersed locations in a flexible and efficient
way. We focus on SD-WAN services based on the Segment Routing over IPv6 (SRv6)
technology. Performance Monitoring solutions are needed in SD-WANs to detect
performance degradation and outages, and optimize network operations.
  In this paper, we describe a high performance solution for end-to-end delay
monitoring for SRv6 based SD-WAN services. The proposed solution leverages the
Simple Two-way Active Measurement Protocol (STAMP) to monitor the delay of an
SRv6 path between two nodes called STAMP Session-Sender and Session-Reflector.
We describe three implementations of the STAMP Session-Sender and
Session-Reflector for a Linux software router and compare their performance. In
particular, two implementations are based on user space processing and one is
based on eBPF. The results show that the eBPF-based implementation outperforms
the user space implementations and has a negligible impact on the forwarding
capacity of the Linux software router.
