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 stored in at least one buffer, 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, by speculatively moving the packets forward even while DMA engines perform their processing to facilitate their transfer.