A system comprising: a switch that receives packets from and delivers packets to one or more devices connected to the switch through a bus; a memory integrated into the switch to store a mapping of virtual addresses to physical addresses; and a non-transitory computer readable storage medium integrated into the switch storing instructions executable by the switch and upon such execution cause the switch to perform operations comprising: receiving, by the switch from one of said one or more devices connected to the switch by the bus, a memory access request that includes a particular physical address; retrieving, by the switch from the memory, a mapping of a virtual address to a physical address in response to receiving the memory access request that includes the particular physical address; determining, using the mapping of the virtual address to a physical address, that the device is not allowed to access a memory location identified by the particular physical address by determining that the particular physical address is not stored in the memory; in response to determining that the device is not allowed to access a memory location identified by the particular physical address, discarding the memory access request; and in response to determining that the particular physical address is not stored in the memory, resetting said one of said one or more devices. a switch that receives packets from and delivers packets to one or more devices connected to the switch through a bus; a memory integrated into the switch to store a mapping of virtual addresses to physical addresses; and a non-transitory computer readable storage medium integrated into the switch storing instructions executable by the switch and upon such execution cause the switch to perform operations comprising: receiving, by the switch from one of said one or more devices connected to the switch by the bus, a memory access request that includes a particular physical address; retrieving, by the switch from the memory, a mapping of a virtual address to a physical address in response to receiving the memory access request that includes the particular physical address; determining, using the mapping of the virtual address to a physical address, that the device is not allowed to access a memory location identified by the particular physical address by determining that the particular physical address is not stored in the memory; in response to determining that the device is not allowed to access a memory location identified by the particular physical address, discarding the memory access request; and in response to determining that the particular physical address is not stored in the memory, resetting said one of said one or more devices. receiving, by the switch from one of said one or more devices connected to the switch by the bus, a memory access request that includes a particular physical address; retrieving, by the switch from the memory, a mapping of a virtual address to a physical address in response to receiving the memory access request that includes the particular physical address; determining, using the mapping of the virtual address to a physical address, that the device is not allowed to access a memory location identified by the particular physical address by determining that the particular physical address is not stored in the memory; in response to determining that the device is not allowed to access a memory location identified by the particular physical address, discarding the memory access request; and in response to determining that the particular physical address is not stored in the memory, resetting said one of said one or more devices.