Methods and apparatus are provided for simultaneously supporting multiple hosts with a single communication port; each host may host multiple functions. The input/output device comprises multiple buffers; each buffer stores packets for one host, but can be dynamically reallocated to a different host. Multiple buffers may simultaneously support the same host and all of its functions. After a packet is received and classified, it is distributed to buffer ingress managers. Within a set of ingress managers serving one buffer, each manager corresponds to one function of the buffer's corresponding host, and is programmed with criteria for identifying packets desired by that function. One copy of the packet is stored in a buffer if at least one of the buffer's ingress managers accepts it, along with control information for processing the packet upon egress from the buffer. Egress managers for each buffer extract packets and transfer them to destination host/functions.