Distributed Router for OVS

Scope

VDR(Virtual Distributed Router) is going to provide an option for user, to creat distributed routers, which allow one-hop forwarding for east-west traffic in virtualized networks. This will dramatically increase the total bandwidth, and also bring other advantages.

Brief Introduction

• The goal of this blueprint is to implement distributed router in openvswitch plugin. Openvswitch plugin is the most popular plugin nowadays. However, lots of people found that under heavy east-west traffic, current l3-agent router becomes the bottle neck. As shown in the figure below:

• With the help of distributed router in ovs plugin, it's not necessary for east-west traffic to traverse network node to get routing decision anymore. Instead, those traffic will be delivered directly from the source hypervisor to the destination hypervisor. As shown below:

• The test result of our POC shows distinct performance imporvement on several aspects. Advantages we can get:
  • 1. East-west total throughput will increase distinctly when more hypervisors are involved.
  • 2. Under high concurrency of east-west traffic, on average, each VM will obtain a better bandwidth.
  • 3. North-south and east-west traffic don't impact each other anymore. North-south traffic enjoys all the bandwidth of router exclusively.
  • 4. No more unnecessary circuitous path, when east-west session happens between two VMs on the same hypervisor.

Performance Comparison

Here is a comparison between original OpenStack and a OpenStack with distributed router.