Do You Have a Five-Nines Network?

Terry Slattery
Principal Architect

Converged networks typically require a higher availability metric than non-converged networks (there are exceptions, typically in the financial world). Five-nines is often referenced as the basic level of availability that traditional telephony networks used as their metric. If you do the math on 365 days X 86400 seconds/day, that winds up being 5.25 minutes per year of downtime.

Network availability can be measured any number of ways, some of which make it much easier to achieve five-nines availability. If I look at any outage that affects more than 10% of the customers and sum that over the year I get one number. But I can also say that since it affected only X% of the customers, I get to pro-rate it by that same percentage, which makes it much easier to achieve a higher availability value.

Whatever the methodology for calculating the availability metric, there are a number of fundamental things that you can do that will improve a network and its availability. I’m writing about what you can do in a series of blog posts at, starting with a blog “Want a Five-Nines Network?

The first blog post talks about what you can do in the network itself. The foremost things are to run one OS version per hardware platform and to keep the hardware up to date. Yes, this can be expensive. Running a five-nines network does cost extra money. But if it makes more money as a result, it is a good investment.


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Nick Kelly

Cybersecurity Engineer, Cisco

Nick has over 20 years of experience in Security Operations and Security Sales. He is an avid student of cybersecurity and regularly engages with the Infosec community at events like BSides, RVASec, Derbycon and more. The son of an FBI forensics director, Nick holds a B.S. in Criminal Justice and is one of Cisco’s Fire Jumper Elite members. When he’s not working, he writes cyberpunk and punches aliens on his Playstation.


Virgilio “BONG” dela Cruz Jr.

CCDP, CCNA V, CCNP, Cisco IPS Express Security for AM/EE
Field Solutions Architect, Tech Data

Virgilio “Bong” has sixteen years of professional experience in IT industry from academe, technical and customer support, pre-sales, post sales, project management, training and enablement. He has worked in Cisco Technical Assistance Center (TAC) as a member of the WAN and LAN Switching team. Bong now works for Tech Data as the Field Solutions Architect with a focus on Cisco Security and holds a few Cisco certifications including Fire Jumper Elite.


John Cavanaugh

CCIE #1066, CCDE #20070002, CCAr
Chief Technology Officer, Practice Lead Security Services, NetCraftsmen

John is our CTO and the practice lead for a talented team of consultants focused on designing and delivering scalable and secure infrastructure solutions to customers across multiple industry verticals and technologies. Previously he has held several positions including Executive Director/Chief Architect for Global Network Services at JPMorgan Chase. In that capacity, he led a team managing network architecture and services.  Prior to his role at JPMorgan Chase, John was a Distinguished Engineer at Cisco working across a number of verticals including Higher Education, Finance, Retail, Government, and Health Care.

He is an expert in working with groups to identify business needs, and align technology strategies to enable business strategies, building in agility and scalability to allow for future changes. John is experienced in the architecture and design of highly available, secure, network infrastructure and data centers, and has worked on projects worldwide. He has worked in both the business and regulatory environments for the design and deployment of complex IT infrastructures.