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Addressing MPLS vs Over-the-Top and other UC & UCaaS Quality of Service Questions

Posted by Kevin Gulley

Apr 28, 2016

When it comes to your UC deployment, whether it be on-prem, hybrid-cloud or UCaaS, I’m sure we can all agree that redundancy is critical.  So is security and your SBC (Session Border Controller).  So is the software you are using.  A lot of thought goes into addressing these issues, determining the best options and delivering a great solution.  UCaaS_MPLS_Over_the_Top_Network.jpgBut when push comes to shove all employees care about is whether their calls have jitter, are cutting in and out, or get randomly dropped.  While working to deliver the highest possible Quality of Service for their UC-platform, a common question businesses ask is “Do we need to run the solution over a dedicated MPLS network or is it OK to send calls over-the-top via the public Internet?”  NOTE:  For those of you that are ready to geek out for 10 minutes, check out all the MPLS details your little heart desires, here.

The answer to that question depends on a number of issues according to Jason Cummings, VP of Network Engineering at ANPI.  “MPLS is a proven technology and it is not going away anytime soon, especially among larger companies with multiple locations.  These businesses are looking for the direct, guaranteed point-to-point connections and additional capabilities around packet prioritization that MPLS can deliver.  This prioritization is important because your data is going over the same MPLS path and using the same bandwidth and that is a finite resource.  Voice and real time traffic must be prioritized.”  He went on to explain that for the majority of businesses out there, especially if they have a single location, MPLS is not necessary to ensure a high QoS.

VoIP Packets, Delivery and Prioritization and MPLS

When it comes to voice, or really any real-time communications, there are three key metrics that every business cares about:

  1. Did all the packets get delivered
  2. Did they arrive on-time
  3. Did the arrive in the proper order

MPLS extends this for multi-location companies by allowing for priority tags to be attached to the packets to ensure each packet arrives with the right priority as they travel along the protected paths from source to destination.  This control is an important addition for some businesses, but that ability to prioritize packets really only becomes an issue in a network where there is congestion - an issue that many small and medium businesses can effectively address.  No congestion, no need to prioritize packets with MPLS.

Dig Deeper:  Check out the Broadsoft Whitepaper - Premise-based vs. Hosted UC: A Cost of Ownership Comparison 

For businesses considering a UCaaS solution and using an over-the-top approach to real-time communications, there are two key aspects to take into account in order to address the congestion concern.  First, getting the packets to your network edge efficiently and in a prioritied fashion, and second, ensuring you have the necessary bandwidth to get the packets where they need to go without delay.

Optimize Network Hardware Configuration to Prioritize Voice Packet Delivery

According to Cummings, for the majority of businesses considering UCaaS most of the quality issues come from their own LAN and that is the place to start.  “Most off the rack business routers in the market today have some kind of mechanism that allows the voice traffic in the customer’s network to be prioritized.  Companies often use more network resources and bandwidth sharing large data files internally than they do bringing voice out to the internet, and that is where conficts and congestion can arise.”  Taking basic steps to configure the equipment in the LAN to prioritize communication packets can pay major dividends in Quality of Service.   Cummings says he has spoken with many companies that are tightly focused on MPLS, when the quality issues can be found in the network itself.

We went into a bit more detail in a recent post when we discussed a common method for assuring priority of voice and communication packets:

The most common method of taking advantage of this capability is called the dual drop scenario.  In this instance the data network has its own port on the switch and the phones have their own port.  According to Mann, “by separating it out this way, you can easily prioritize the voice and conferencing packets and you are in a better position to deliver a quality experience to your team.” Another way to think about the importance of packet prioritization is, would you rather wait a few extra seconds for your email to show up or experience jitter on twenty percent of your phone calls?  Having the right hardware to prioritize communications packets is critical.

Making Sure You Have Enough Bandwidth for Over-the-Top UCaaS

Once you have your voice packets prioritized and delivered to the network edge and ready to go out over the internet, the next key is making sure you have enough bandwidth to avoid congestion.  But how much is enough?  Lucky you, we covered that in the same post!

...businesses should use the 1 to 6 rule as a starting point.  “The rule of thumb is that businesses need to plan for one active phone call for every six users.  So if you have 60 employees, there will be 10 ongoing calls at any given time...more if you have  a contact center.”  

Toll quality calls require 80Kb per second, per call, so if a business needs to support 10 calls at a time the upload / download speed for voice calls alone is 800K per second.  “Of course that is the baseline.  Companies needs to leave extra room for overhead, extra usage and data,” says Mann, “They also need to take into consideration richer forms of communication like video conferencing, web conferencing and collaboration.”

So is MPLS right for your company?  It’s likely if you’re a medium or larger organization with multiple locations.  If not, look first at ensuring you can prioritize voice traffic on your LAN and that you have enough bandwidth (and then some) to support your UC deployment or your connection to your UCaaS provider.   Actually, you should do that even if you are going with MPLS ;o)  Let us know how you think about this challenge in the comments section below.

Topics: Technology, Voice, cloud, networking, Business Case