A fully programmable memory management system optimizing queue handling at multi gigabit rates

Abstract

Two of the main bottlenecks when designing a network embedded system are very often the memory bandwidth and its capacity. This is mainly due to the extremely high speed of the state-of-the-art network links and to the fact that in order to support advanced quality of service (QoS), per-flow queuing is desirable. In this paper we describe the architecture of a memory manager that can provide up to 10Gbs of aggregate throughput while handling 512K queues. The presented system supports a complete instruction set and thus we believe it can be used as a hardware component in any suitable embedded system, particularly network SoCs that implement per flow queuing. When designing this scheme several optimization techniques have been evaluated and the most cost and performance effective ones used. These techniques minimize both the memory bandwidth and the memory capacity needed, which is considered a main advantage of the proposed scheme. The proposed architecture uses a simple DRAM for data storage and a typical SRAM for keeping data structures-pointers, therefore minimizing the system's cost. The device has been fabricated within a novel programmable network processor designed for efficient protocol processing in high speed networking applications. It consists of 155K gates and occupies 5.23 mm/sup 2/ in UMC 0.18 /spl mu/m CMOS.