6. Network Lower-Level Protocols
Network I/O is processed by many different layers and protocols, including the application, the protocol libraries, the TCP/IP stack, and the network interface driver. DTrace allows you to examine the internals of each layer, tracking a packet step-by-step as it is processed from the application to the network interface. Using DTrace, you can answer questions about system network load such as the following.
• What clients are requesting network I/O?
• To which TCP or UDP ports?
• Which processes are generating network I/O? Why?
• Are packets being dropped in the TCP/IP stack? Why?
As an example,
connections is a DTrace-based tool you can use to trace inbound network connections:
Network-sniffing tools, such as ...