SD-WAN "on the fingers": pros, cons, pitfalls

A few days ago, I was once again asked: “Is SD-WAN pure marketing or really effective technology?”. Mistrust is clear: everything new - and technology is only a couple of years - the market is eyeing with suspicion.

I will try to talk about what SD-WAN is, to whom and why such solutions are needed, as well as what are their pros and cons.

What is it and for what

When we talk about SD-WAN — software-defined distributed networks — we mean solutions for managing the network and transferring data between the center and the branches.

As for the main characteristics and tasks that are usually put in front of SD-WAN, this is usually intelligent traffic control, which is transmitted from the center to the branch and back. Also for software-defined networks characterized by a single point of management of the entire infrastructure and monitoring.
')
Usually it looks like this: there is a certain central platform, there are branches. Everywhere should be installed devices that will work with the technology of software-defined networks. The entire configuration of this distributed wealth comes from a single point - the controller. For any configuration changes, the controller, at the request of the administrator, distributes updates to other devices located in the branches.

In the case of a large number of branches, any typical procedures for changing the configuration usually take a fairly large amount of time. In the case of SD-WAN, it will be different: just configure one device and transfer all this over the network further. From here we have a reduction in operating costs for infrastructure management.

In addition to configuration management tasks, the controller also assumes the role of a monitoring point. It monitors the distributed network. The administrator does not need to go to each device in case of any changes in the network.

If the monitoring reveals a problem: a drop in the communication channel, deterioration of the channel characteristics, an increase in signal delay, etc., this is immediately monitored and displayed in the corresponding panel. You can see both the current and historical load of the channel, track the bursts of the load of a particular branch. Everything is pretty clear.

What else is needed

Rarely when in large organizations - banks, retail, etc. - there is only one communication channel. Usually two or more. This serves as a guarantee of the resiliency of the branch.

I think any employee of retail can be raised at night and ask: how much is an hour of idle shop. And he will clearly answer - these are mandatory numbers that are easily considered. Or a bank branch. What happens if it is left without communication? Probably, many people remember the recent failure on the network of one of the largest Russian operators. So, one of the main problems for people was the inability to confirm payments and transfers. Communication was not only half a day, and the victims are still complaining.

The presence of more than one channel requires appropriate administration — there are certain difficulties associated with this: how you can reach this branch, how we will allow traffic to it.

For example, we need to intelligently distribute application traffic - say, voice traffic should be sent only through the channel with the best characteristics, through the carrier VPN. Less demanding traffic — email traffic — to run through a cheaper channel with a smaller SLA. It takes quite a long time to set up, and if you multiply it by the number of branches, it becomes a serious task.

SD-WAN solves this problem and allows you to dynamically, in real time, check all available communication channels in a branch office, and, based on the requirements of a specific application - for example, voice communication - direct traffic along the best path. This is one of the main concepts of such products, which is not only implemented by Citrix. But what distinguishes our solution is per packet data transfer.

The traffic of any application is presented to us as a certain set of packets that are transmitted to the channel, depending on the conditions that exist here and now. If there is voice traffic, the operator channel is available and everything is fine with it, then the packet will go there (where we set up). If something is wrong with the operator’s network, the package will go through another channel within the same conversation. The user will not notice at all that something has happened - only the administrator will know about this when he reads the logs. The performance of the application and the user will not suffer.

Who needs it

Any organization with a large number of branches. When the branch office infrastructure becomes more complicated and there are problems with the stability of the communication channels - an SD-WAN can be the solution

What are the advantages of technology

The main advantage, in my opinion, is the possibility of combining several communication channels into one logical one. And, accordingly, intellectual redistribution of traffic depending on the type of application between these channels.

Cons and pitfalls

For a company that is going to update the fleet of its branch network equipment, I do not see cons. SD-WAN is the most modern solution for managing the work of branches and for traffic distribution. There are no contraindications as such. But if you have already managed to buy classic equipment - that, alas. Abrupt changes will entail certain difficulties. That, however, depends only on the budget of the organization.