The Rise of the Out-of-Band Management Network

Cloud and virtualization share a common attribute: dynamism. That dynamism comes at a price…

Let’s talk about management. Specifically, let’s talk about how management of infrastructure impacts the network and vice-versa, because there is a tendency to ignore that the more devices and solutions you have in an infrastructure the more chatty they necessarily become.

In most organizations management of the infrastructure is accomplished via a management network. This is usually separate from the core network in that it is segmented out by VLANs, but it is still using the core physical network to transport data between devices and management solutions. In some organizations an “overlay management network” or “out-of-band” network is used. This network is isolated – physically – from the core network and essentially requires a second network implementation over which devices and management solutions communicate. This is obviously an expensive proposition, and not one that is implemented unless it’s absolutely necessary. Andrew Bach, senior vice president of network services for NYSE Euronext (New York Stock Exchange) had this to say about an “overlay management network” in “Out-of-band network management ensures data center network uptime”

Bach said out-of-band network management requires not only a separate network infrastructure but a second networking vendor. NYSE Euronext couldn't simply use its production network vendor, Juniper, to build the overlay network. He described this approach as providing his data center network with genetic diversity.

"This is a generalized comment on network design philosophy and not reflective on any one vendor. Once you buy into a vendor, there is always a possibility that their fundamental operating system could have a very bad day," Bach said. "If you have systemic failure in that code, and if your management platform is of the same breed and generation, then there is a very good chance that you will not only lose the core network but you will also lose your management network. You will wind up with absolutely no way to see what's going on in that network, with no way to effect repairs because everything is dead and everything is suffering from the same failure."

"Traditionally, in more conventional data centers, what you do is you buy a vendor's network management tool, you attach it to the network and you manage the network in-band – that is, the management traffic flows over the same pipes as the production traffic," Bach said.

Most enterprises will manage their data center network in-band by setting up a VLAN for management traffic across the infrastructure and dedicating a certain level of quality of service (QoS) to that management traffic so that it can get through when the production traffic is having a problem, said Joe Skorupa, research vice president at Gartner.

Right now most enterprises manage their infrastructure via a management network that’s logically separate but not physically isolated from the core network. A kind of hybrid solution. But with the growing interest in implementing private cloud computing that will certainly increase the collaboration amongst infrastructure components and a true out-of-band management implementation may become a necessity for more organizations – both horizontally across industries and vertically down the “size” stack.