OpenStack faces an uncertain long-term future at AT&T after a senior executive involved with the company's SDN and NFV program declined to rule out replacing it with an alternative technology.

Asked if OpenStack was "here to stay" during an interview with Light Reading, Rupesh Chokshi, an assistant vice president with the US telco, said: "It is difficult to say whether it will be replaced or not but right now that is what we have in the infrastructure delivering services."

Chokshi did not say what technologies might replace OpenStack but raised doubts after flagging AT&T's interest in using microservices and containers, which have been seen as a potential threat to the open source, cloud-computing platform.

"If there are better ways of doing things those will be part of the ongoing process," he said.

The comments come at a difficult time for OpenStack, which counts AT&T Inc. (NYSE: T) as one of its chief supporters in the service provider community.

In the enterprise sector, a number of organizations have turned their backs on OpenStack and are instead investing in cloud-agnostic platforms based on the concept of containers. (See Mirantis Pivots as OpenStack Loses 'Wow Factor'.)

Widely seen as an alternative to running comparatively clunky virtual machines, containers essentially aim to package software in a more lightweight and manageable way.

Mirantis Inc. , a vendor that previously billed itself as "the pure-play OpenStack company," may have fueled concerns in April when it announced plans to start supporting Kubernetes, a high-profile container technology.

Also in April, chipmaker Intel Corp. (Nasdaq: INTC) withdrew financial support for the OpenStack Innovation Center project, while in December last year networks giant Cisco Systems Inc. (Nasdaq: CSCO) shut down its Intercloud platform, which was based on OpenStack. (See Intel Pulls Funding From OpenStack Development Group and Cisco Shutting Intercloud Multi-Cloud Platform.)

OpenStack is not necessarily incompatible with Kubernetes, and the OpenStack community has previously made efforts to embrace container technologies.

But as "alternative open source approaches to cloud resource management," containers are certainly a "complication" for both operators and vendors, industry analyst Caroline Chappell told Light Reading back in late 2015. (See OpenStack Doubts Surface After BT Ultimatum.)

For more NFV-related coverage and insights, check out our dedicated NFV content channel here on Light Reading.

AT&T is not the first operator to suggest that another technology could replace OpenStack.

The UK's BT Group plc (NYSE: BT; London: BTA) launched a stinging attack on OpenStack during an industry event in late 2015, threatening to abandon it in favor of a proprietary technology unless it overcame several technical challenges. (See BT Threatens to Ditch OpenStack.)

BT's criticisms did not relate to any interest in containers, although Peter Willis -- the BT research executive who voiced anxiety -- has recently highlighted the attractions of containers over virtual machines in various scenarios. (See BT: Telco Mindset Could Negate Container Benefits.)

Elsewhere, however, there is still plenty of support for OpenStack, which received a boost earlier this month when UK-based Vodafone Group plc (NYSE: VOD) picked Mirantis as an OpenStack partner for its Ocean virtualization program. (See Mirantis Sails Into Vodafone Ocean.)

The technology also continues to underpin the network transformation at AT&T, which has made a big commitment to open source more generally.

That commitment has seen the operator release its ECOMP software platform into the open source community under the auspices of the Linux Foundation. (See Will ECOMP Be the Alpha MANO? .)

More recently, ECOMP has come together with OPEN-O, another open source MANO (management and network orchestration) initiative, to form ONAP. (See MANO Marriage: ECOMP, OPEN-O Converge as ONAP.)

Despite this consolidation, there is still concern about a bifurcation of industry efforts on MANO, with the Open Source MANO initiative -- which features a number of major European telcos -- charting a different course from ONAP.

Chokshi insists the momentum behind ONAP is growing but acknowledges that open source technology faces some big challenges.

"You do worry about keeping the quality and performance and reliability," he says. "When you are buying something very proprietary a part of what you pay for is that it will work … but the value add [of open source] is all about the innovation and speed [of development]."

Interoperability, or the lack of it, is also "a problem in the industry," says Chokshi, although one he believes ONAP can help tackle by continuing to release specifications into the broader community.

— Iain Morris, , News Editor, Light Reading