A pipeline configuration is described for use in network traffic
management for the hardware scheduling of events arranged in a
hierarchical linkage. The configuration reduces costs by minimizing the
use of external SRAM memory devices. This results in some external memory
devices being shared by different types of control blocks, such as flow
queue control blocks, frame control blocks and hierarchy control blocks.
Both SRAM and DRAM memory devices are used, depending on the content of
the control block (Read-Modify-Write or `read` only) at enqueue and
dequeue, or Read-Modify-Write solely at dequeue. The scheduler utilizes
time-based calendars and weighted fair queueing calendars in the egress
calendar design. Control blocks that are accessed infrequently are stored
in DRAM memory while those accessed frequently are stored in SRAM.