In its simplest form, First In First Out (FIFO) queuing, also known as first-come, first-served queuing, buffers and forwards packets in the order of their arrival.
FIFO has no concept of priority or classes of traffic and consequently, makes no decision about packet priority. There is only one queue, and all packets are treated equally. Packets are sent out an interface in the order in which they arrive, as shown in the figure. Although some traffic may be more important or time-sensitive based on the priority classification, notice that the traffic is sent out in the order it is received.
-
