Simplify network configuration for VMs by harmonizing multiple Bridging, QOS, DCB and CNA implementations


One Line Summary

Simplify network configuration for VMs by harmonizing multiple Bridging, QOS, DCB and CNA implementations


Libvirt has a few basic APIs to provide QOS via libcgroups however it cannot provide guranteed I/O bandwidth to VMs

With improvements in ethernet bridging technologies like DCB, libvirt should be able to administer DCB tlvs and thus provide protocol based QOS for different service protocols like iSCSI, RDMA, FCoE etc via libcgroups, by implementing hooks into the dcb layer.

An architecture based on libvirt ensures that different DCB implementations provide their pluggins to libvirt thus simplifying cross-vendor implementations.

While DCB will ensure ethernet QOS and prioritization of various protocols, cgroup controllers in the kernel can ensure I/O bandwidth across the kernel stack.

A solution like this invovles building consensus among multivendor DCB implementations in the kernel since some NIC vendors implement this in the firmware and some in the kernel making CNA configurations look ugly. Simple tasks like configuring VLANs for CNAs becomes vendor dependent.

There is also a need to plumb different load balancing algorithms in the storage network I/O path to work in unison. This is increasingly relevant since the kernel is introducing new network bridging technologies(macvtap), new load balancers in DM, network schedulers, and existing loadbalancers in bonded configurations.

There is need to plumb this together to make userspace network configurations of these technologies look sane.


Virtualization, iSCSI, DCB, QoS, Userspace Network Configuration


  • Shyam Iyer



    Shyam Iyer is a senior software engineer in Dell’s Enterprise Linux Engineering group enabling Dell PowerEdge Servers and Storage for the Enterprise Linux Operating Systems. Most recently, he lead RHEL6 engineering efforts for Dell’s PowerEdge Server’s and currently works as an onsite partner for Dell at Redhat.

    His interests encompass Linux Kernel Debugging, Server Platform bringup, iSCSI, Virtualization technologies architectural development, performance tuning and white papers.

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