• Even though there are ways to see what OVS/OVN is doing with a particular packet, there is no way to know why

• OVN/OVS to generate packet samples enriched with some OVN metadata that can be easily correlated back to SDN-specific objects or other human-readable pieces of information that provide insights of what the SDN is doing with a packet and why

• Drop sampling
• These samples will contain metadata that can be correlated to the specific place in the OVN pipeline where the drop took place (useful for debugging and support) and human-readable explanations that can be shown to customers

• Network Policy Correlation
• Network Policy correlation consists in OVN/OVS generating samples for traffic that goes through specific ACLs (i.e: Network Policies). These samples will contain enough information to correlate them back to the exact Network Policy or policies that the packet went through
• If there are multiple network policies in a service chain policy correlation should be able to map out the network policies along with the nodes / endpoint information for the point of enforcement information

• Sampling Enrichment
• Enrichment for topology 
• Enrichment for network policy

Metrics Collection Context / Metadata

(1) Topology Context

(2) Policy Context

     (a) Security Policy

From a use case perspective, we can think about 2 use cases

(1) Monitoring

(2) RCA

Monitoring PoP metadata may be further divided into

• Port/Interface (excluding flow level metrics)

• Node

• Instance

• System (PMD, compute resource …)

• NIC

• Flow level

NOTE: Sampling infrastructure for OVN relies on kernel datapath ebpf hooks producing netlink samples monitored by a consuming agent. This Epic follows this implementation. It means that this Epic does NOT cover scenarios when kernel datapath is not used (DPDK). A separate design / Epic will be needed if we are interesting in sampling NFV workloads.

Draft design document covering the possible Sampling integration with RHOSO can be found here: https://docs.google.com/document/d/1l5vHBiZvOLt8BMCQFQxxb_eUiqptRuv6PyGQ5Go5Tdg/edit Please consult the document if you are working on any of the stories attached to this Epic. The document does not cover all the necessary details, but should be a good first guidance.