MPLS in the Air
Verizon Wireless takes a step in the right direction with a QoS option for its Verizon Private Network service that lets businesses designate priority for some data.
Last week I ran into an interesting Verizon Wireless webinar regarding the carrier's new Private Network Traffic Management service. The basic service has been around for several years, but got an important refresh back in September.
In essence, the service provides wireless users with Multi-Protocol Label Switching (MPLS)-like security and quality of service (QoS), albeit a rather stripped-down version of the latter. Given the wireless industry's obsession with the consumer market, anything that the mobile operators do that has a business focus is worth of our attention.
Verizon Private Network launched several years back as a secure wireless data service that operates in conjunction with Private IP, the carrier's wired MPLS service. Rather than using a secure VPN tunnel to ensure data sent over the wireless network remains private, the Verizon Private Network extends a secure MPLS connection over 4G LTE or other wireless data services. In truth, the over-the-air encryption used in modern cellular networks is already pretty good, but the Verizon Private Network and Private IP services together ensure end-to-end security.
Now, with Private Network Traffic Management, Verizon has added a limited QoS capability that lets users give higher priority to a portion of their data traffic. As with wired MPLS, user devices would have to set the Differentiated Services Code Points in the headers of any packets they want assigned to that higher-priority class. Verizon refers to the higher priority as "Business Critical," as opposed to the traditional "Best Effort" class.
With the traffic management solution, organizations using Verizon Private Network can apply three levels of service to any or all of their wireless lines: Public Safety, Premium, and Enhanced. As the name indicates, Public Safety is limited to use by government agencies like first responders; the other two are available to all businesses. Public Safety and Premium allow prioritization of 2 Mbps of traffic, while the Enhanced service level allows 500 Kbps of priority traffic. Public Safety also gives higher-priority access to the radio channel.
As with the Expedited Forwarding (EF) class of service in traditional MPLS, any packets sent in excess of the 2-Mbps or 500-Kbps limits will be discarded. This means applications will need to be designed carefully if they are to make use of this capability.
In traditional MPLS, we would do a voice traffic study to determine the number of simultaneous connections (what we used to call "trunks") needed. We would then compute the number of bits, including all header information, needed to provide them, order the required amount of EF capacity, and then use call admission control to limit the number of calls set up over that interface. This would protect against packet discard. I am not quite sure how this process would work with a smartphone.
The other big question is: How "high" is "higher" priority? With wired MPLS, the carrier specifies the service's worst-case performance for delay, jitter, and packet loss for each class of service (typically jitter is only specified for the EF class). Given the nature of wireless service (i.e., all users in a given cell or sector are sharing one data channel), Verizon said it can't quote specific performance parameters. It said, however, that it has run tests and has numbers it can share with prospective customers -- but it didn't share them with me. Verizon doesn't disclose pricing on its website either, though you can order the new service for any of your wireless lines.
A Good Start
Clearly a service like this is a boon to public safety, particularly for first responders in large-scale emergencies. It harkens back to the type of priority access carriers used to provide to police, fire, and other emergency services in the PSTN. However, as wireless is becoming a necessity rather than a convenience, having the ability to prioritize particular applications can be useful. In the webinar, Verizon made reference to usefulness for Internet of Things applications, but each business is going to have its own priorities.
We'd like to see carriers roll out lots of other business-oriented wireless services, particularly a wireless Centrex capability such as discussed off and on over the past 20+ years -- but at least this Business Critical class of service is a step. I'd like to think that the mobile operators have discovered the need to serve business customers and have come to an understanding that their needs are different from consumers' -- and they don't have to do with megapixels.