In short
SASE vs SD-WAN is the whole versus a part. SD-WAN chooses the best path for each site's traffic across broadband, leased lines and mobile links, with failover. SASE combines SD-WAN with a cloud security service edge (SSE), so branch and remote traffic is inspected under one policy. SD-WAN alone suits sites with local security; SASE suits distributed, cloud-first organisations.
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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, 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, 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 SSE, and for the general definition, SASE on our Cloud Security site.
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 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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When SD-WAN alone is enough, and when to add 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 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 and you want ZTNA vs VPN answered at the same time.
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.
How branch traffic reaches the security cloud
However you buy it, branch traffic has to get from the site into the SSE. The common routes are:
- Automated tunnels from the vendor's own SD-WAN. Cisco SD-WAN (Catalyst SD-WAN) and Meraki SD-WAN can set up tunnels to Cisco Secure Access automatically, which Cisco describes as single-vendor SASE. Check Point SASE includes its own SD-WAN in the platform.
- IPsec tunnels from an existing firewall or router. Most SSE platforms accept standard IPsec from a site edge. Todyl's SASE Tunnel option, for example, connects an office or cloud network into Todyl's Secure Global Network over IPsec. Our ZTNA vs IPsec page explains why site-to-site IPsec still has a place in a zero trust design.
- 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 gateway that WatchGuard FireCloud Total Access uses to reach private resources.
The NCSC's ZTNA reference architectures 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.
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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, describes its SASE SD-WAN as failing over across MPLS, 5G and broadband. Many organisations keep MPLS for a contract term or for specific applications, put SD-WAN over the top and retire MPLS later. If you are reviewing circuits at the same time, Forever Group covers leased line options.
SD-WAN and SASE examples we can supply
| Route | SD-WAN part | Security part | Fits |
|---|---|---|---|
| Cisco single-vendor SASE | Cisco Catalyst SD-WAN or Meraki SD-WAN | Cisco Secure Access (SSE) | Cisco and Meraki estates; see Cisco SASE |
| Cisco dual-vendor | Your existing SD-WAN | Cisco Secure Access over IPsec | Organisations keeping a current SD-WAN |
| Check Point SASE | SD-WAN in the platform | Internet Access, Private Access, SaaS Security | One vendor for users and sites; see Check Point ZTNA |
| Exium | Cyber Gateway (software NGFW with SD-WAN), per site | Exium SASE Essentials or Pro, per user | Smaller multi-site organisations; see Exium |
| WatchGuard | Firebox SD-WAN | FireCloud Internet Access or Total Access | WatchGuard Firebox estates |
| Todyl | Your existing edge, via SASE Tunnel (IPsec) | Todyl SASE | Agent-led SASE with simple site links; see Todyl SASE |
These are routes, not rankings. The choice depends on what is already installed, contract dates, how many sites and users you have, and who will run it. All the platforms are compared on SASE providers.
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, SSE only or full SASE, and plan the order of change around your contract dates. Forever Group supplies Meraki networking and 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 ZTNA and SASE
We are an independent IT and cyber security provider. We supply and support several zero trust access and SASE platforms, so we can recommend what fits how your people work rather than one vendor's answer to everything.
- Assess first: we look at your current VPN, firewall, identity set-up and the applications people need to reach before suggesting anything new
- Vendor-aware advice across ZTNA, SSE and SASE options, including Cisco Secure Access and Check Point Harmony SASE
- Pilots and phased roll-out: we can help you start with one group of users or one application, then extend access policy by policy
- VPN replacement: planning the move away from remote access VPNs, including identity provider integration and device posture checks
- Ongoing support: policy changes, licence reviews and renewals, with the details confirmed at quote
We work with businesses, schools, charities and public sector organisations. Pricing depends on users, features 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 an 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.
Is SD-WAN secure on its own?
SD-WAN tunnels between sites are normally encrypted, and some SD-WAN appliances include a firewall, but that protects traffic through the site only. Remote users and SaaS use need separate controls, which is what SSE adds.
Can I use my existing SD-WAN with SASE?
Usually. Most 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 SSE. SD-WAN helps most where there are several sites or where link resilience matters.
Still deciding?
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