1996 – 2020
The practitioner
Two decades inside the networking and security industry, building, breaking and fixing the systems - and, from 1997, teaching them at every one of those roles.
This is the long middle of the story, and the reason the teaching that came later carries weight. For roughly two decades, the work was implementation: designing networks, standing them up, troubleshooting them under pressure, and being the person called when something critical broke. The journey ran through some of the defining names in networking, on two continents.
Cabletron and Enterasys, 1996 to 2000
The formal career began in 1996 at Cabletron Systems, then a leading networking equipment vendor based in Rochester, New Hampshire, as a field network engineer intern - the first assignment being to read the company's 1992 guide to local area networking cover to cover. The internship became a four-year full-time position. Over four and a half years in total, the role spanned field engineering and post-sales support, systems engineering and pre-sales, and, from 1997, certified instruction. The subject matter was the enterprise LAN and WAN of the era: switches, routers, Wi-Fi and WLAN, network management, NAC and UAC, and stateful-inspection firewalls. Cabletron was also Cisco's largest reseller at the time, through the OEM line that integrated Cisco IOS and Cisco routing into the MMAC hubs, and I was one of the experts for it: the feature explanations and configuration examples I carried to customers came from the internal documentation CDs Cabletron sent its offices, the ones we called "Jeopardize" discs for the warning on them that distributing the CD or its confidential contents would seriously jeopardize one's job. In 2000, Cabletron reorganized into four companies, and the part this career touched became Enterasys Networks.
Riverstone Networks, Santa Clara, 2000 to 2002
The next chapter was in California. Riverstone Networks, a Cabletron spin-off building metropolitan-area network equipment, brought a move to Santa Clara, first on an L-1 intracompany transfer and then, in 2001 and 2002, on an H-1B work visa. The role was Tier-III product support engineer and knowledge-management coordinator: third-level technical escalation, recreating customer scenarios in the lab, regression testing and bug verification, and building the knowledge base that the rest of support relied on. The technologies were the backbone of the early-2000s carrier and metro world: Gigabit Ethernet, MPLS, metropolitan-area switching and routing, and BGP. This period also produced a formal milestone: as part of the visa process, a United States evaluation in 2001 recognized an educational background equivalent to a bachelor's degree in computer science and a bachelor's degree in business administration.
Cisco Systems, Brasília, 2003 to 2004
Back in Brazil, and contracted through Cisco Professional Services, the role shifted toward the customer relationship at its most demanding. As a high-touch operations manager and single point of contact, the work was post-sales customer-satisfaction management for two of Brazil's largest federal entities, SERPRO, the government's data-processing agency, and ECT-Correios, the national postal service. The technical surface was Catalyst switches and routers, PIX firewalls, and CSS, CSM, and ACE load balancers, but the real work was escalation management and keeping critical national infrastructure running smoothly.
Enterasys again, then Juniper, 2005 to 2010
The second half of the decade returned to the vendor side as an enterprise LAN subject-matter expert. At Enterasys from 2005, the focus was switches and routers, Wi-Fi and WLAN, network management, NAC and UAC, and intrusion detection and prevention, across solution design, implementation, auditing, and training. From 2009, at Juniper Networks through Professional Services for LATAM, the role was new-product advocacy for the strategic partner Telefónica Empresas in Brazil, centered on EX switches and SRX firewalls, with operations training on Junos-SRX delivered at Level 3 and Impsat, now Lumen.
The channel and consulting years, 2010 to 2020
The final decade of this era moved fluidly between roles, all of them building toward the instructor the story arrives at. There were stints as a network and security engineer through resellers and distributors, deepening expertise in enterprise switching and routing, firewalls and next-generation firewalls, SSL-VPN, user access control, WAN acceleration, and internet load-balancing across Juniper and Cisco solutions. Crucially, this period included the pivot toward F5, beginning work with F5 BIG-IP that would define the years to come. Across all of it, technical training was a constant thread, never absent from any role.
The sites of those years, 2004 to 2019
The web kept its own record of this era. From 2004, nutzmann.net presented Nützmann Networks, the consultancy constituted in São Paulo in 2003, with its services, a partner roster, a mission page built around return on investment and three small tools: a bits-and-bytes calculator, an IP addressing calculator and a cabling pinout. From 2013, ntz.com.br carried the same company as NTZ Tecnologia: consultancy, specialised services, forty-hour courses taught by an instructor since 1999, a remote laboratory of real equipment, and a chronology of engagements back to the Brasília contract. A rebuilt site of 2017 to 2019 listed competences by vendor, with F5 as the main focus. Every capture is linked from the page on the earlier sites.
By 2020, the picture was complete: someone who had not just studied these systems but lived inside them for twenty years, on the vendor side and the customer side, in design and in crisis. That is the difference an implementer brings to a classroom. When this person explains why a configuration behaves a certain way, it is because they have seen it behave that way, at three in the morning, with a critical service waiting.