A process that calls send() on a TCP socket expects the bytes to leave the machine eventually. It does not expect the call to wait until the...
Draft placeholder for the full transmit path article. Full content will be updated.
A NIC that has just finished DMA-ing a frame into a host ring buffer does not copy the payload in its hard interrupt handler. The handler do...
A packet from a laptop in Mumbai to a server in Frankfurt does not ask the Internet for the shortest path. It follows a route that some netw...
A process that accepts ten thousand TCP connections cannot afford to ask the kernel about each socket in turn. select(2) and poll(2) copy ...
A kernel module can do almost anything. That is why loading one is a privileged act and why a bug in one can take the machine with it. eBPF ...
TCP can carry bytes in order. It cannot tell you who is on the other end, and it cannot stop a path observer from reading those bytes. HTTPS...
TCP names a connection by four numbers: two addresses and two ports. Change any of them and the connection is gone. It also delivers one ord...
TCP can deliver a reliable byte stream. That is useful when a file must arrive complete and in order. It is the wrong contract when a late p...
HTTP can fetch a page. TCP can keep a reliable byte stream open. Neither explains why a live chat box updates without a refresh or why a tra...
HTTP can describe a request. DNS can find an address. Neither of those steps moves a single reliable byte across an unreliable network. That...