In short
SD-WAN suits multi-site businesses that need better links between offices; SASE suits those that also want cloud security for every site and remote user. SD-WAN picks the best path across leased lines, broadband and mobile, with failover. SASE joins it to a Security Service Edge (SSE) under one policy, often added at a router or MPLS renewal.
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What SD-WAN does, and what it does not
SD-WAN (software-defined wide area network) replaces fixed routing between offices with policy-based routing across several links at once. Each site has an SD-WAN appliance or virtual edge that watches link health, such as latency and packet loss, and steers each application over the best available path: a leased line (opens in a new tab), business broadband or a 4G or 5G backup. If one link fails, traffic moves to another. Sites are usually provisioned centrally, which makes rolling out new branches quicker.
What SD-WAN does not do on its own is decide whether a user should reach a website, a SaaS app or a private application. Some SD-WAN appliances include a firewall, but that firewall only protects traffic passing through that site. Staff at home, on the road or at a client site are outside it.
What SASE adds
SASE (secure access service edge) joins SD-WAN to a Security Service Edge (SSE): a provider's cloud that applies a secure web gateway (opens in a new tab), CASB, zero trust network access and usually firewall as a service. Office traffic reaches that cloud through tunnels from the SD-WAN edge; remote users reach it through an agent or browser. Everyone gets the same policy, wherever they are.
The difference in one line: SD-WAN gets traffic there; SASE also checks it on the way. For the security half on its own, see SASE vs Security Service Edge (SSE), and for the general definition, what is SASE.
SASE vs SD-WAN compared
| SD-WAN | SASE | |
|---|---|---|
| Main job | Reliable, application-aware connectivity between sites and the cloud | Connectivity plus cloud-delivered security for sites and users |
| Who it covers | Sites | Sites and remote users |
| Security | Whatever the edge appliance includes, for that site | SWG, CASB, ZTNA and usually FWaaS in the provider's cloud |
| Where policy lives | The SD-WAN controller | One policy across networking and security, or two linked platforms |
| Remote access | Usually a separate VPN | ZTNA through the same platform |
| Typical licensing | Per site or appliance | Per user for the Security Service Edge (SSE) plus per site or appliance for SD-WAN |
| Typical trigger | Router or MPLS refresh, need for resilience | VPN replacement plus branch refresh, cloud-first strategy |
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Tell us what matters most to you and we will recommend one, with the trade-offs explained.
When SD-WAN alone is enough, and when to add Security Service Edge (SSE)
SD-WAN on its own can be the right answer when most staff work on site, the main problem is link resilience or cost, and each site already has a firewall you are happy with. A multi-site business on ageing routers, with few remote workers, may simply need better connectivity.
Add a Security Service Edge (SSE) when any of these are true:
- Staff work remotely or hybrid and their web traffic is either unprotected off-site or backhauled through the office over a VPN.
- Applications have moved to SaaS, so sending traffic to head office for inspection adds delay for no benefit.
- You want one set of web, SaaS and access rules for everyone instead of a policy per site firewall.
- A remote access VPN is due for replacement; see SASE vs VPN.
Go to full SASE when both are changing at once: branch connectivity is due for refresh and you want security to follow users and sites from the same platform. Our ZTNA vs SASE page shows the layers side by side.
SD-WAN and SASE integration: single-vendor and dual-vendor
However you buy it, branch traffic has to get from the site into the Security Service Edge (SSE). There are two integration models.
Single-vendor: SD-WAN and security from one supplier
- Cisco: Cisco documents automated site-to-site IPsec tunnels (opens in a new tab) from Cisco Catalyst SD-WAN into Cisco Secure Access, and presents Meraki SD-WAN with Secure Access as an integration on its Secure Access page (opens in a new tab). See Meraki SD-WAN (opens in a new tab) on cloudnetworking.uk for the Meraki side and Cisco SASE for the combination.
- HPE: HPE describes HPE Networking EdgeConnect (opens in a new tab) as a secure SD-WAN that is "the foundation for a unified SASE architecture", with a built-in firewall and path selection across Security Service Edge (SSE) points of presence. See HPE Aruba Networking SASE.
- Barracuda: Barracuda SecureEdge (opens in a new tab) brings ZTNA, firewall as a service and web security together with "fully integrated office connectivity with Secure SD-WAN".
- Check Point: Check Point SASE (opens in a new tab) includes SD-WAN in the platform, with failover across MPLS, 5G and broadband links.
Dual-vendor: one vendor's SD-WAN tunnelling into another's security cloud
- IPsec tunnels from an existing SD-WAN, firewall or router. Most Security Service Edge (SSE) platforms accept standard IPsec from a site edge, and Cisco publishes an integration guide (opens in a new tab) for Secure Access with HPE Aruba Networking EdgeConnect SD-WAN. Todyl's SASE Tunnel option, for example, connects an office or cloud network into Todyl's Secure Global Network over IPsec.
- A software gateway at the site. Exium's Cyber Gateway is a software next-generation firewall with SD-WAN that runs on a virtual machine, in the cloud or on general-purpose hardware, managed alongside Exium SASE.
- The site firewall as the gateway. WatchGuard Firebox appliances provide SD-WAN, and a Firebox can act as the FireCloud Gateway (opens in a new tab) that WatchGuard FireCloud Total Access uses to reach private resources.
The NCSC's ZTNA reference architectures (opens in a new tab) describe the same pattern from the security side: connectors or gateways at the edge of each network segment set up outbound tunnels to the policy engine, so private applications do not have to accept inbound connections from the internet. Single-vendor and dual-vendor trade-offs are compared on single vendor SASE.
Weighing up the options?
We can compare them against your own requirements and recommend what fits.
Zero trust SD-WAN and the zero trust branch
SD-WAN on its own is not zero trust: it connects sites and steers traffic, and anything allowed onto the branch network can usually reach a lot of it. "Zero trust SD-WAN" and "zero trust branch" describe adding three things to the site:
- Segmentation at the site, so printers, cameras, card terminals and guest devices sit apart from staff devices and servers. HPE, for example, says EdgeConnect can "enforce Zero Trust in branch offices" with a built-in firewall providing IDS/IPS, URL filtering and role-based segmentation.
- Per-application access, so a user in the branch reaches the applications their role needs and no more, using the same ZTNA policy they get at home.
- Cloud inspection, so web and SaaS traffic from the branch goes through the Security Service Edge (SSE) with the same rules as remote users.
ztna.org.uk covers the segmentation side in zero trust network segmentation (opens in a new tab). On a SASE platform, the SD-WAN edge, its local firewall and the Security Service Edge share the policy, which is what makes the branch part of the zero trust design rather than a trusted zone.
SASE vs MPLS
MPLS is a private WAN run by a carrier: predictable, but every site's internet traffic is often backhauled to a central breakout, and adding sites takes time. SASE flips that. Sites connect over internet links managed by SD-WAN, and security happens in the provider's cloud close to the user.
It need not be either-or. SD-WAN can use MPLS as one of its links: Check Point, for instance, lists failover across MPLS, 5G and broadband for its SASE SD-WAN. Many organisations keep MPLS for a contract term or for specific applications, put SD-WAN over the top and retire MPLS later. The underlay still matters: leased-lines.uk explains leased line resilience (opens in a new tab) options for the sites that need them most.
SD-WAN and SASE routes we can supply
| Route | SD-WAN part | Security part | Fits |
|---|---|---|---|
| Cisco single-vendor SASE | Cisco Catalyst SD-WAN on Cisco 8000 Secure Routers (opens in a new tab), or Meraki SD-WAN | Cisco Secure Access | Cisco and Meraki estates; see Cisco SASE |
| Cisco dual-vendor | Your existing SD-WAN, such as HPE Aruba Networking EdgeConnect | Cisco Secure Access over IPsec | Organisations keeping a current SD-WAN |
| HPE | HPE Networking EdgeConnect | HPE's Security Service Edge (SSE) | HPE Aruba Networking estates; see HPE Aruba Networking SASE |
| Check Point SASE (opens in a new tab) | SD-WAN in the platform | Internet Access, Private Access, SaaS Security | One vendor for users and sites; see Check Point SASE |
| Barracuda SecureEdge | Barracuda Secure SD-WAN | ZTNA, firewall as a service, web security | Organisations wanting inspection in the cloud, at the branch or on the device; see Barracuda SecureEdge |
| Exium | Cyber Gateway (software NGFW with SD-WAN), per site | Exium SASE, per user | Smaller multi-site organisations; see Exium SASE |
| WatchGuard | Firebox SD-WAN | FireCloud Total Access | WatchGuard Firebox estates; see WatchGuard SASE |
| Todyl | Your existing edge, via SASE Tunnel (IPsec) | Todyl SASE | Agent-led SASE with simple site links; see Todyl SASE |
These are common routes. The choice depends on what is already installed, contract dates, how many sites and users you have, and who will run it. Vendor facts from Cisco (opens in a new tab) and Cisco's EdgeConnect integration guide (opens in a new tab), HPE (opens in a new tab), Barracuda (opens in a new tab) and Check Point (opens in a new tab), checked 9 November 2026. All the platforms are compared on SASE vendors.
How Forever Systems helps
We look at the WAN and the security together, so a branch refresh and a VPN replacement do not end up as two separate projects that undo each other. We can review your sites, circuits, firewalls and remote access, recommend SD-WAN only, Security Service Edge (SSE) only or full SASE, and plan the order of change around your contract dates. We can also supply SD-WAN hardware and business connectivity, so the WAN and security plans can line up. Scope and timescales are confirmed at quote, and pricing depends on sites, users and components, so ask us for a quote. Contact us to start.
How Forever Systems helps with SASE
Forever Systems supplies several SASE and Security Service Edge (SSE) platforms, so we can recommend the one that fits your sites, your people and the network and security kit you already run.
- Assess first: we look at your current VPN, firewalls, WAN links and identity set-up, and the applications people need to reach
- Help you choose: single-vendor or dual-vendor SASE, or Security Service Edge (SSE) first and SD-WAN later, matched to what you need now
- Pilots and phased roll-out: we can help you start with one group of users or one site, then extend policy step by step
- Licensing in one place: subscriptions can be billed monthly, with terms confirmed at quote
We work with businesses, schools, charities and public sector organisations. Pricing depends on users, sites, components and term, so ask us for a quote.
Frequently asked questions
Is SD-WAN part of SASE?
Yes. SASE combines SD-WAN networking with a cloud Security Service Edge (SSE). SD-WAN on its own handles routing and resilience between sites but does not apply cloud security to remote users.
Does SASE replace SD-WAN?
No. SASE includes SD-WAN or works with it. If you already have SD-WAN, you can add a Security Service Edge (SSE) and tunnel sites into it, which gives you dual-vendor SASE.
What is the difference between SASE and MPLS?
MPLS is a private carrier WAN that often backhauls internet traffic to a central site. SASE uses SD-WAN over internet links and inspects traffic in a provider's cloud. SD-WAN can still use MPLS as one of its links during a transition.
What is zero trust SD-WAN?
SD-WAN that also segments devices at the site, gives users per-application access and sends branch traffic through a Security Service Edge (SSE), so the branch is not treated as a trusted network. On a SASE platform these share one policy.
Can I use my existing SD-WAN with SASE?
Usually. Most Security Service Edge (SSE) platforms accept IPsec tunnels from existing SD-WAN or firewalls, and some vendors document integrations. We can check compatibility with your current kit before recommending a route.
Do small businesses need SD-WAN?
Not necessarily. A single office with a reliable leased line and mostly remote staff may only need a Security Service Edge (SSE). SD-WAN helps most where there are several sites or where link resilience matters.
Still deciding?
Ask us and a member of our team will get back to you.