In the future, partners see Cisco building a solution that will directly compete against VCE's Vblock and VxRack.

Partners also predict new moves from Cisco in the future that will strain the VCE partnership.

"I could see Cisco teaming up with NetApp using SolidFire for software-defined storage, or maybe they buy someone themselves, combine it with Cisco Nexus [switches] and CliQr and pulling all that together tightly – plus the HyperFlex for the ROBO – they would have a VxRack and VxRail similar play," said the CRN SP500 partner.

The reports from partners of trouble ahead for the VCE partnership come even as  CEO Chuck Robbins and Dell CEO Michael Dell shook hands last week and pledged their allegiance to their VCE alliance in a face-to-face video interview. VCE's $3 billion Vblock business contains Cisco UCS servers and networking solutions.

Cisco declined to specifically comment to CRN regarding its future relationship with VCE, saying that the Robbins and Michael Dell video "says it all."

When contacted, a Dell spokesperson also pointed to the video as well as an open letter recently published by Michael Dell to customers and partners pledging his support to Cisco and VCE.

"After joining with Dell, VCE's close working relationship with Cisco will continue. Vblock will continue to follow Cisco's compute and networking roadmaps and EMC's storage roadmaps to bring the latest technologies to VCE customers," wrote Michael Dell in the letter. "We know that VCE is a centerpiece of EMC's 2016 plans, and we are extremely enthusiastic about VCE's future and our continued partnership with Cisco."

Partners said the recent campaigning by both sides is an attempt to reassure VCE customers that their VBlock investment is safe. Even before Dell announced its intentions to acquire EMC, solution providers said the writing was appearing on the wall that Cisco, which sold most of its VCE stake in 2014, was moving away from VCE.

In 2015, VCE launched its new VxBlock converged infrastructure system that offers VMware – now majority-owned by Dell -- NSX software-defined networking (SDN) technology for the first time. Vblock originally only supported Cisco's ACI, the company's SDN technology that competes against NSX. VCE offers customers both ACI and NSX options.

VCE last May launched its VxRack hyper-converged infrastructure line using white-box servers.

Cisco, meanwhile, unveiled its competing hyper-converged offering, HyperFlex in March.