Enhanced Ethernet for Data Center: Reliable, Channelized and Robust

Abstract

Data Centers today deploy multiple fabrics for LAN, SAN and IPC traffic. This introduces significant cost, complexity and management challenges. Hence there is strong demand for consolidating these multiple fabrics. Ethernet is default fabric used primarily for LAN traffic and it is low-cost, well-known, widely available, and broadly compatible. So, it makes an ideal candidate for such IO consolidation. However, current Ethernet suffers from certain deficiencies that need to be addressed. Legacy Ethernet suffers from 3 main issues (a) Lack of congestion management mechanism -which results in packet drops when network is congested. This also results in unpredictable latencies for the traffic through these congested networks, (b) No standard mechanism for traffic differentiation on the link which will protect all the traffic types on consolidated link. Only mechanism available is 802. lp strict prioritization without any bandwidth assurance, (c) Poor utilization of available bandwidth in the network. Spanning Tree Protocol tends to remove links that can cause loops in the network. This results in lower bisectional bandwidth. Underlying Layer 2 protocols do not allow any multipathing techniques that are available in other technologies like Fiber Channel, Infiniband etc. This paper presents a framework of solution that includes multiple enhancements to Ethernet network -that will improve legacy Ethernet significantly for Data Center deployment. Some of these enhancements are being pursued in IEEE and IETF for standardization. IEEE 802.1Qau Task Force is focusing on improving congestion management capabilities of Ethernet IEEE 802.1Qat and IETF-TRILL is focusing on improving bisectional bandwidth by allowing L2 multipathing capabilities for complex and large DC deployments. Other efforts include mechanisms for better traffic differentiation and improved link level flow control for data center -Ethernet. This paper will elaborate more on congestion management related work.