A talk by C. Scott Andreas (@cscotta) of Boundary on "the network" and designing / deploying distributed applications. This session offers a deep-dive into how application-level problems manifest at the network level. Some of these cases range from basic network partitions and node outages to sophisticated application-level changes such as garbage collections on managed runtimes, classes of bugs which evade conventional monitoring but constitute partial failures, changes in network activity based on database partitioning, load balancing, and sharding, and other warning signs that crop up at layer three long before wreaking havoc at layer seven as customer-visible failures begin to occur. Combining application-level metrics with network analytics is a powerful cocktail for identifying hot spots quickly, and connecting the dots out to the client closes the loop.