4G LTE Connected Retail- Part One Network Assessment

During a conversation with a project manager who works for one of my vendors recently, I was informed that a project we worked on together in 2019 became the model for a new service offering from that vendor in the 5G space. Given this information, I think its fair to share my experiences on the project and some lessons learned.

In early 2019 my team was asked to engage in a cost reduction exercise to eliminate our costly T1 circuits and run our data traffic on our 4G LTE backup connections. Given the relative speed difference between T1 and 4G we jumped at the opportunity to help the organization reduce costs and increase throughput on the WAN-Edge. Originally, my intention was to use this project as the basis for a Six Sigma Green Belt (ultimately this was put on hold due to the pandemic).

What I cannot stress to people enough from the outset of such a project, is that you must, absolutely must, understand both your network and your provider's network before taking on such a transformative project.

Some organizations may be using some specialty configurations that enable the use of dynamic routing protocols over cellular networks. Other organizations may not be able to support some of the specific requirements for that network due to equipment limitations and could be configured differently.

If you are using a Private 4G Network (Read this as a carrier-hosted VRF), there is a good chance that this Private Network (Frequently identified as an APN) is directly connected into your MPLS or WAN Private Network if your carrier for Cellular and WAN are from the same vendor. If you have this scenario, at some point the Private Wireless Network must be dropping the traffic from the cell towers into your MPLS network.

You'll want to validate the circuit size (my deep suspicion is this nothing but a bandwidth command on a L3 Switch interface somewhere) and QoS policies (do you know how much traffic you're going to be pushing?) where the wireless network meets wired. If you implemented cellular as a backup, there's good chance you did not design this interconnect with the throughput and traffic protection to support all of your traffic.

If you are using a Public 4G Network, you are going to have other considerations. Are you running full SD-WAN? Do you have to backhaul all your traffic for security reasons? If you are cutting MPLS, my guess would be your traffic is largely centralized still. This gives you a couple of concerns. How much Internet bandwidth do you have? Can your main Internet circuits handle all the bandwidth if you are going to hairpin? Can you terminate all these IPSEC tunnels on your existing gear without changing it out?- Or, do you need throughput or VPN licenses, modules, dedicated hardware? Is it possible to standup dedicated gear only for this purpose? Maybe this is the time to implement SASE....

If your business uses voice over the network (who doesn't?), you've got some more questions to answer. What does your voice network look like? Are you running a SIP over the network to your locations? Are you terminating POTS lines locally to FXO ports with centrally or locally registered telephony endpoints? The key point to identify here is; How is your traffic going to be treated as it hits the cell tower? We'll get further into this in a later post, but make certain you understand how your voice services are delivered, even if its "not your job".

In my next post on this topic I'll cover how the answers to these questions impact design and some of the considerations that should be made.

Thanks for reading!