Methods, systems, and apparatus, including computer programs encoded on computer storage media, for storing an address in a memory of a switch. One of the systems includes a switch that receives packets from and delivers packets to devices connected to a bus without any components on the bus between the switch and each of the devices, a memory integrated into the switch to store a mapping of virtual addresses to physical addresses, and a storage medium integrated into the switch storing instructions executable by the switch to cause the switch to perform operations including receiving a response to an address translation request for a device connected to the switch by the bus, the response including a mapping of a virtual address to a physical address, and storing, in the memory, the mapping of the virtual address to the physical address in response to receiving the response.