By David Le Goff – 6WIND Product Marketing Manager
With the widespread industry discussions about Software Defined Networking (SDN) and the OpenFlow protocol, this is an appropriate time to review some of the key SDN performance challenges and how 6WIND’s software addresses them.
Architectural concepts
OpenFlow improves network management by centralizing network control functions and is currently designed to work with Layer 2 and Layer 3 packet forwarding engines.
The 6WINDGate packet processing software maximizes the performance of high-end networking equipment by enabling a single control plane to manage an arbitrary number data plane nodes, distributed over multiple blades or racks, providing full support for both homogeneous and heterogeneous systems. This distributed architecture includes the 6WINDGate IP-based management protocol running between the control plane and data plane, maximizing scalability at the system level. OpenFlow-based systems required the same level of distribution, addressed in 6WINDGate through an OpenFlow agent.
Figure 1: 6WINDGate’s Distributed Architecture Reflects OpenFlow Concepts
SDN systems need to extend beyond Layer 3 and improve virtual switch performance
In future, many categories of SDN-based systems will need to incorporate Layer 4 through Layer 7 equipment in order to ensure reliability and security.
In the case of application server blades, the number of VMs per blade is increasing rapidly, leveraging on-going improvements in the performance of the processors used on those blades. Today, a typical server blade hosts around 20 VMs, with that number expected to grow to hundred within a few years. Because of this growth, the data center network needs to expand beyond its current limit at the Top-of-Rack, to the point where a virtual switch on each server blade is used to distribute the increasing volume of network traffic to virtualized applications. This implies the need for a high-performance virtual switch solution that is not constrained by the I/O performance limitations of standard hypervisors.
Also adding to the networking load now placed on server blades, multi-tenant architectures serving applications for multiple users require traffic engineering (ACL, tunneling, QoS etc.) to be performed at the server edge in order to provide users with individual, differentiated services. This requires advanced packet processing functions running at high performance in a virtualized environment.
Figure 2: Network Virtualization From Layer2 to Layer 7 Functions
As well as performance bottlenecks imposed by the guest OS of each virtual appliance, both the hypervisor kernel stack and associated virtual switch functions add significant overhead.
Through optimizations for Intel® Architecture platforms as well as unique hypervisor enhancements, the 6WINDGate software maximizes networking performance on commodity hardware platforms. To address the networking performance issues within the kernel stack, 6WIND provides virtual NIC support as part of its enhanced Intel® DPDK support, enabling significant performance improvements compared to standard OS stacks. This includes full support for both emulated and para-virtualized NIC drivers within standard hypervisors.
Together with its unique fast path technology, the enhanced I/O virtualization support in 6WINDGate enables OEMs to sustain high-performance networking in virtualized environments.
The virtual switch function provides network overlays (tunneling) within the server, for use in multi-tenant architectures where tunnels implement support for unlimited number of virtual networks, bypassing the 4K limitation of VLANs.
One of the proposed approaches for network overlays relies on Generic Routing Encapsulation (GRE, RFC 2784) and uses some of the optional GRE field headers to build multi-tenant-aware tools for traffic analysis, traffic inspection, and monitoring with a 24 bit identifier, allowing up to 16 million virtual subnets in the same management domain, in contrast to the limitations of VLANs.
The following graph illustrated the GRE performance delivered by 6WINDGate, which improves significantly on standard GRE implementations.
Figure 3: 6WINDGate GRE Performance
System benefits
6WIND provides solutions that address the key performance challenges inherent in disruptive networking technologies such as OpenFlow.
By providing both network performance enhancements for virtualized architectures and a rich set of optimized Layer 2 through Layer 7 networking protocols for Intel® Architecture platforms, fully-compatible with standard hypervisors, the 6WINDGate software solves network performance bottlenecks and enables advanced networking functions to run at high performance, both on virtual switches instantiated on application servers and also on virtual network appliances.
These features represent critical business advantages for data center operators as they work to address both CAPEX and OPEX challenges in the face of on-going increases in users, in data traffic and in cloud workload complexity.
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