Is SD-WAN better than MPLS?

SD-WAN is something everyone's talking about but is it better than MPLS? My answer is yes... and it's easier to explain than baseball.

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Lately, our clients with an MPLS WAN are starting to ask: “Should we get rid of our MPLS and go to SD-WAN? Is SD-WAN better?”

I don’t mean to make this question sound childish (since it’s a fantastically good question), but it reminds me of a mistake I made when my 9-year-old son asked me a question the other day.

He is obsessed with baseball, so, of course, he asked me something all of us baseball fans have wondered at some point: “Daddy, which is better… a guy who hits .250 with 50 home runs or a guy who hits .300 with 10 home runs?”

I should have just answered it with “Homers, baby… everyone buys tickets to see dingers!” I would have sounded manly, plus, he would have laughed and walked away content.

But instead, I went all baseball-nerdy on him: “Well, that depends. How many RBIs does each have? What about their batting average, with runners in scoring position? Who else is on the team?” … etc, etc.

He and I discussed it for ten mind-numbing minutes. Then, he eventually walked away more confused than ever. Baseball just got way too complicated.

So, I’m gonna try not to do this to you. The whole “it depends” reply is always true but how about I just forget the outlier situations and tell you what I think… shooting from the hip, in generalities?

So, here is my quick, rough-around-the-edges opinion, based on only two scenarios.

SD-WAN is better than MPLS if your company doesn’t run real-time apps over the WAN

If your company has a lot of mission-critical, real-time apps running over the WAN (i.e. your phone calls, video conferencing or remote desktop), MPLS might still trump SD-WAN or at least for this traffic type. Although it brings a lot of benefits to the table, SD-WAN still uses the public Internet to connect your sites. And once your packets hit the pubic Internet, you will not be able to guarantee low levels of packet loss, latency and jitter: the killers of real-time applications.

The slight exception is if your company’s real-time applications are hosted in the cloud (as opposed on on-prem), and you are considering using a Cloud-Enabled SD-WAN solution (like I explained in this previous Network World blog) … which you will read more about below.

Here’s the good news. If the vast majority of traffic on your company’s WAN is comprised of non-real-time applications, such as email, file sharing, software, etc., SD-WAN can bring the following benefits over MPLS:

  • Increased bandwidth:

With MPLS, if you need 100M+ bandwidth, monthly circuit costs will often make your hair stand on-end. Sometimes it’s the router costs and sometimes it’s the circuits themselves but the point is, high-bandwidth MPLS is usually pricy.

SD-WAN, however, allows your company to utilize multiple, high-bandwidth, inexpensive Internet connections, simultaneously (i.e. business-class cable, fiber, 4G, etc.). By aggregating multiple connections, your company will experience fast Internet speed at a low cost.

  • Increased performance:

SD-WAN will throttle low-priority traffic on-the-fly and (if you have multiple ISP connections), always send your traffic across the Internet circuit with the fastest route.

MPLS will not perform either of these actions. With MPLS, there is only one network connection and your Class of Service (CoS) settings are static, without the ability to adjust on-the-fly.

  • Increased uptime:

By allowing your company to aggregate multiple ISP Internet and WAN connections at a single site, your company will have seamless circuit redundancy for your WAN, across multiple circuit types and service provider networks.

MPLS providers sometimes have a failover to a secondary Internet connection but it’s typically not instantaneous and it’s almost never able to have a 3rd option.

  • Increased performance at small, remote or international sites:

Nearly every company has sites which are not a good fit for their MPLS network because they are either too small (and cannot justify the high cost of an MPLS circuit), or they are not serviceable by their MPLS provider (because they are in a remote or international location where their MPLS provider does not have network). In these locations, companies with MPLS are typically forced to suffer through less-than-desirable performance as they run all traffic over an IPsec VPN.

To the contrary, SD-WAN is provider-agnostic and will deliver the same benefits, no matter which underlying ISP your company is using.

  • No longer imprisoned by your ISP:

With MPLS, you must have the same MPLS service provider at all sites, making it an all-or-nothing relationship.

As a result, it takes a whole lot of reasons to make you want to go through the hassle of switching your company’s MPLS provider. You are stuck… which is how your MPLS provider loves it.

With SD-WAN being ISP agnostic, your company is never stuck in ISP prison and can add and remove ISP’s at any site, any time, with ease.

Cool benefits, right? As this article from Fierce Telecom describes, this is why companies are often keeping a reduced-size MPLS network for their real-time applications and still adding SD-WAN for all other WAN applications (i.e. a “Hybrid WAN”).

SD-WAN is better than MPLS if your company is using the cloud

As I mentioned above, Cloud-Enabled SD-WAN solutions are game changers if your company is using a lot of applications hosted in the cloud, such as Amazon Web Services, Office 365 and Salesforce.

With a Cloud-Enabled SD-WAN service provider, your on-site SD-WAN box sends your traffic to a cloud gateway, which then connects you to your cloud applications and keeps your cloud sessions running, even while it reconnects you to a better circuit. For instance, if you have hosted VoIP and a user is on a phone call… if you lose your primary Internet connection, the user will not lose their call because the cloud gateway keeps the session constant while it reconnects to your site’s secondary Internet connection, within milliseconds.

In addition, some Cloud-Enabled SD-WAN providers have direct connections to the major cloud service providers. This means once your traffic hits your SD-WAN provider’s nearest cloud gateway, you connect directly to your cloud provider (as opposed to having to continue traversing the public Internet to reach them). This means less latency, packet loss and jitter… which equates to a better user experience with your company’s cloud applications.

Some MPLS service providers offer a direct connect feature for certain cloud providers but none of them offer the ability of a cloud gateway to keep your session constant as it reconnects you to a backup connection.

I hope I did a better job answering the question than I did answering my son’s baseball question. Are you still interested in SD-WAN? As always, don’t be shy. Contact me with questions or comments.

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