Title: “SwitchScope: A View from the Inside”

Abstract: Running a modern network requires constant diligence to maintain efficiency and reliability for customers. This is made challenging by the fact that the life of a packet inside each switch is complex, and yet currently quite hard to observe and debug. Packets entering a switch may be dropped (by access control policy or a full queue), or delayed (by a long queue) or modified (by policy) before heading to the next hop. Prior telemetry systems allow network operators to analyze flows that a switch sees, but they do not grapple with the internals of the switch’s multiple pipelines.

In this talk, I will discuss our contributions towards SwitchScope, a flexible telemetry system that utilizes programmable (PISA) switches, and which allows debugging switch configurations and determining the source of bottlenecks or lost packets. I will detail our work on an expressive query language that provides network operators insight into the life of packets in a switch, as well as our compilation strategies to support useful queries about lost packets while minimizing the use of switch resources.