Zero-trust network access (ZTNA) and secure access service edge (SASE) models have proven to be vital in today's security landscape, but they don't represent the end-all-be-all of network security, according to AT&T Chief Security Officer Bill O'Hern.

AT&T's secure access network edge model is an evolution of both SASE and zero trust in relation to network deployment and practical support, O'Hern explained in a blog post. While ZTNA and SASE are useful security tools overall, they alone cannot fully protect the three main types of network access — physical business locations, end users working from anywhere, and third parties that require B2B access.

"[Zero trust and SASE] do require considerable adjustment to support the challenges of handling modern hybrid networks, legacy systems, mergers and acquisitions, and other unique one-off scenarios," O'Hern wrote.

To that point, AT&T's secure access network edge model provides a level of holistic network security that would be unlikely using preexisting security models alone.

The customer network zone includes corporate offices, third-party suppliers, and end users. In this case, "we agree with the SASE model that access should be delivered using a smart edge, and our AT&T team has been innovating heavily in this area," O'Hern said, citing the operator's work with virtualization and SDN at the edge.

The next two zones are the access network and AT&T network zones, which are embedded into the operator's service infrastructure. These components represent the means through which AT&T's 4G LTE, 5G, and broadband networks are deployed from an internal core to broad geographic coverage.

The final edge locations and cloud interconnect zones are where devices connect to the cloud in a move away from traditional data center compute to cloud-based applications and workloads.

"My advice is that you start thinking about this new, evolving model as a mash-up of both zero trust and SASE – but in the context of practical network deployment and support," O'Hern said, adding that AT&T is in the process of further developing this model for both businesses and governments.