Apparatus and method for dynamically limiting output queue size in a quality of service network switch

A method for sending a frame of data from a first channel to a second channel, comprising:

• reserving q of n available buffers of m total buffers to the first channel;
• storing a frame that is received from the first channel in i of the q buffers and changing the status of the i buffers to unavailable;
• selectively assigning the frame to the second channel based on j buffers of the m total buffers assigned to the second channel and h buffers of the m total buffers neither reserved nor assigned to any channel, wherein i+j≦m and h+q≦n;
• assigning the i buffers storing the frame to the second channel if the frame is assigned to the second channel;
• changing the status of the i buffers to available if the frame is subsequently sent over the second channel;
• and
• discarding the frame and changing the status of the i buffers to available if the frame is not assigned to the second channel,
• wherein q, n, m, j, i, and h are integers.