On designing of an EOS chip with SDP

As is known, Ethernet has gained great popularity in LAN (local area network). Meanwhile, SDH/SONET is the backbone of today´s communication networks. Then, how to exchange information between Ethernets located in different regions over SDH/SONET is becoming a hotspot. This paper provides a single chip solution of Ethernet transmission over SDH/SONET (EOS), which supports up to thirty-two 10/100Mbit/s Ethernet ports of four 1000Mbit/s Ethernet ports over 2.5Gbit/s SDH/SONET. On designing of this EOS chip, we also present a packet loss policy called SDP (selective dropping policy) to perform flow control, which can actively select packets to drop as the packet buffer overflows. Up to now, we have developed two policies of SDP: LPF (longest packet first) and LSPF (least significant packet first). Simulation results show that with LPF, the average packet loss rate (PLR) of the overall system can be cut down significantly without increasing the buffer storage, and with LSPF, the packets of the least important group is discarded discriminately in the case of overflow to lower average PLRs of other groups. Moreover, SDP can cooperate with Ethernet´s backpressure mechanism fairly well and be implemented easily on chip.