Episode 180: Asymmetric Routing, Multicast Flooding, and ACL Misconfigurations

Some network issues are subtle, involving advanced concepts like asymmetric routing, multicast flooding, and access control list (ACL) errors. This episode explains how asymmetric routing—where traffic returns on a different path than it arrived—can confuse firewalls and lead to dropped packets. We discuss how to diagnose and design around this behavior using symmetric paths and session tracking.

Next, we cover multicast traffic that floods segments due to missing IGMP snooping, and how ACLs applied in the wrong direction or with missing statements can break services silently. These are the kinds of advanced problems that separate good network techs from great ones—and this episode gives you the tools to join the latter group.