Keeping Tills and Calls Running at Peak: A Retail Guide to Network Traffic Priority

On the busiest trading day of the year, everything in a store competes for one connection: card terminals, store phones, stock lookups, signage downloads and shoppers on the guest WiFi. When the line is full, the router has to decide what goes first. Without rules, it treats a card authorisation the same as a shopper streaming video.

Retail network traffic priority means classifying store traffic so payments and voice get guaranteed bandwidth ahead of guest WiFi and background updates. Paired with a second circuit or a 4G/5G backup, it keeps tills trading through congestion and through a failed line.

TL;DR

• Decide which traffic wins before peak, not during it. Payments and voice go first; guest WiFi and updates go last.
• Keep payment traffic on its own network segment. It narrows PCI DSS scope and keeps guest devices away from tills.
• Priority only helps while the line is up. A second path with sub-second failover covers the times it isn't.
• Apply one policy to every store from one console, so no shop drifts from the standard.

What is network traffic priority in a retail store?

It's a set of rules that tells the store router which data to send first when the connection is busy. It's usually built with Quality of Service (QoS) markings, which tag each packet with a class so the router can queue it accordingly.

In a quiet hour, priority makes little difference because there's spare bandwidth for everything. It matters when demand exceeds capacity: a Saturday in December, a product launch, or a promotion that sends shoppers onto the guest WiFi while staff are taking card payments.

The IETF's RFC 4594 sets out the common model. It defines service classes such as Telephony and Signalling and recommends applying the same markings consistently, so equipment from different vendors treats traffic the same way.

Which store traffic should get priority?

Payments and voice come first because they fail visibly and immediately. Background traffic comes last because nobody notices a delayed download.

Two cautions apply. Priority doesn't create bandwidth: if the circuit is undersized, giving payments the top class only decides who suffers. And the classification should match how your stores actually trade, which is why a traffic audit comes before any configuration.

How does traffic priority support PCI DSS compliance?

Priority and segmentation are separate controls, but they're usually configured together, and segmentation is the one with a compliance impact. Keeping payment traffic on its own segment, apart from guest WiFi and corporate traffic, reduces the number of systems inside PCI DSS scope.

The PCI Security Standards Council's Guidance for PCI DSS Scoping and Network Segmentation says segmentation isn't a PCI DSS requirement but is strongly recommended as a way to limit which systems need PCI controls. On a managed private network, DigitalWell separates voice, data, guest and POS traffic into distinct virtual routing segments (VRFs), so a compromised guest device has no path to a card terminal.

DigitalWell provides the connectivity tills and card terminals run on. Payment processing stays with the retailer's existing payment provider.

What happens to tills when a store connection fails?

If the store has one circuit and it fails, priority rules stop mattering, because nothing gets through. Brendan Power at DigitalWell, who works with the company's connectivity customers, puts the retail stakes simply:

"A lot of the retail shops, if something goes wrong, your tills don't work, and you can't have any transactions." Brendan Power, DigitalWell

The answer is a second path. DigitalWell SD-WAN uses dual internet circuits with optional 4G/5G backup. The FortiGate appliance in each store monitors every link and moves traffic to the secondary path in under a second when the primary degrades. The decision is made locally on the appliance, so it doesn't wait for a central controller.

The priority rules travel with the traffic. When a store falls back to 4G, the narrower link makes classification more important, because payments and voice must take the limited capacity first.

Should retailers use SD-WAN or MPLS for priority traffic?

Most multi-site retailers fit SD-WAN, because their applications have moved to the cloud and they need to add stores quickly. MPLS still suits estates that need private network isolation or carry heavy real-time voice between sites.

DigitalWell can overlay SD-WAN on an existing MPLS contract, so retailers don't need to wait for expiry. Insomnia runs DigitalWell connectivity across 70+ stores, and its case study reports recurring WiFi and broadband issues eliminated and faster card payments.

"With DigitalWell's solution, connectivity issues are becoming a thing of the past. Even when issues flare up, these are easily remedied with minimal downtime." Conor Ward, Head of IT, Insomnia

How should a retailer set up traffic priority across its stores?

Start with what the stores carry today, then write one policy and push it everywhere.

• Audit traffic at a sample of stores. Measure what runs over each circuit at peak, including your busiest store and your smallest.
• Agree the classes with operations, not only IT. Store and contact centre managers know which failures cost sales.
• Segment before you prioritise. Put payments, voice, corporate and guest traffic on separate segments, then apply QoS classes.
• Cap guest WiFi. Limit the share of the circuit guest devices can take, so a full shopping centre doesn't starve the tills.
• Move updates overnight. Firmware and content downloads should never compete with trading traffic.
• Add a second path at every trading site. Leased units in shopping centres and train stations often need landlord permission for a new fixed line; a 4G/5G backup needs no new cable into the unit.
• Manage the policy centrally and test failover before peak. Apply the same rules to every store from one console, and review link usage after each busy period.

Frequently Asked Questions

Does QoS help if my store broadband is too slow?

Only partly. QoS decides which traffic goes first; it doesn't add capacity. If payments and voice alone exceed the circuit at peak, the store needs a faster circuit or a second one.

Should guest WiFi run on the same connection as tills?

It can share the physical circuit if it sits on a separate segment with a bandwidth cap. Without both, guest devices compete directly with card terminals.

How fast is SD-WAN failover?

DigitalWell SD-WAN fails over in under one second. The FortiGate appliance in the store detects the degraded link and moves traffic itself, so staff and callers don't notice.

Can we apply the same traffic rules to every store?

Yes. DigitalWell manages policy centrally through FortiManager, so one rule set applies across 3 sites or 50, and new stores get the same policy on day one.

Does DigitalWell process card payments?

No. DigitalWell provides the resilient connectivity tills, card terminals and payment systems run on. Payment processing stays with your existing provider.

Key Takeaways

• Payments and voice belong in the top traffic classes; guest WiFi, signage content and updates belong at the bottom.
• Segmenting payment traffic narrows PCI DSS scope, which the PCI Security Standards Council strongly recommends.
• Priority can't help a store whose only line is down. Dual circuits or 4G/5G backup with sub-second failover keep tills trading.
• A traffic audit comes first, because priority doesn't add bandwidth to an undersized circuit.
• One centrally managed policy keeps every store, including new ones, on the same standard.

Want to know how your stores would cope at peak? Ask DigitalWell's retail team for a store traffic audit before your busiest weeks, or see how DigitalWell supports retail.