Customers have typically had only a couple of options for how to back up the unified communications implementations in their branch offices, but software-defined networking (SDN) is delivering another, more flexible option that could be attractive in a number of situations.
So-called SD WAN offerings promise to enable companies to use multiple, relatively inexpensive Internet connections to back up the connections to cloud-based UC solutions.
Today, most customers use one of two approaches to ensuring survivability of UC implementations in their branches, depending on how their UC setup is configured.
Survivable Branch Options for Centralized UC
If it’s a centralized configuration, where all calls come in to a central “on premise’ UC location and then fan out to the branches over the corporate WAN, the issue is what happens when that WAN goes down. Branches would be left in the cold, with no communications capabilities at all.
In such an instance, it’s common to have some sort of survivable branch client that can use a backup line so users can at least make and receive calls, make 911 calls and such. But that won’t address the issue of how employees within the branch can collaborate using UC with one another.
For that, customers need some survivable branch software that provides base UC functions, including presence and instant messaging. Sonus Networks, for example, has survivable branch software that runs on its session border controllers (SBC) integrated with companies like Microsoft and Broadsoft, says Mykola Konrad, VP of Go to Market and Strategic Alliances for the company.
“If you’re going to put SIP calls through, you’ll have an SBC at the branch anyway,” Konrad says. “It’s much better if it can also run software that allows the main UC instance to be backed up and survivable.”
Backing Up Cloud-based UC with SD WAN
The second approach applies to where customers are using a cloud-based UC solution rather than an on premise solution. A Survivable branch appliance can also be used here for specific sites, but the difference is that the entire UC system in this case is in the cloud. Here the main issue is backing up the WAN link to the cloud-based service because if it goes down, all users are out of luck.
One option is to have multiple MPLS links from your headquarters location to the UC service provider. “The problem with that is it starts to get expensive,” Konrad notes, given MPLS may cost $250 to $500 for a 10M bps link (depending on region). It can also be complex to manage and configure. Do you want both links active all the time, or one active and one passive? Or are you actively routing among them in a round-robin fashion?
“That kind of routing is harder to do than you think with standard routers,” he says. “It’s hard to configure and maintain for IT departments, especially if you have lots of sites.”
Another option that is just starting to take hold is to use SDNs and SD WAN offerings. The idea is to create a hybrid WAN that leverages SDN technology to route traffic among multiple active links.
“And rather than use MPLS, you can use plain Jane Internet links,” Konrad says. Say you need 10M bps of bandwidth to the headquarters site. Instead of one MPLS link that may cost $200 or more, along with another for backup, you can instead get four 2M bps plain Internet links, which may cost <$50 each. Intelligent routing software, such as the Sonus NaaS IQ platform, takes care of routing packets among the four links. If one goes down, the software still has three others to choose from.
“The market is evolving to that sort of architecture, especially in the UC space, but we’re in early stages,” Konrad says. In the meantime, the survivable branch appliance is also applicable for users of cloud-based UC services, giving branch users at least a base level of UC functions should the WAN link be down.