Network SLA Methodologies

Terry Slattery
Principal Architect

My prior post Network SLAs – Which one to use? about SLAs described calculation methodologies.  But what data must be collected for those calculations and what’s a useful calculation methodology?

A business with high availability requirements may prefer an SLA that measures connectivity availability.  This business must determine the required connectivity and determine how to measure it.  One method of measurement might be counting lost pings between sites or monitoring with IPSLA (Cisco specific).  This type of business typically has a highly redundant network, so measuring SLA based on devices and links isn’t very useful.  The monitoring system needs to run tests over the important communication paths and record all connectivity failures.  Totaling the failures across the network would yield the availability SLA.    Financial organizations typically build these types of networks.

A different organization that has less stringent connectivity requirements may use the same monitoring methodology, but averages the availability measurements across all sites.  This business will typically have the ability for remote sites to operate while disconnected, which is why averaging network downtime across sites is an acceptable measurement.  There can be significant savings in equipment and links in this business model.  A manufacturing business may use this model, where remote sites can run independently for a few hours or a few days.

Device-level SLAs might be applicable in parts of an organization and the networking team needs to decide if it is best to average device downtime or to sum the total downtime, or both.  A food packaging company might use a device-centric SLA, summing all downtimes for devices that are key to the processing, packaging, and shipping process.  Many of these companies cannot shut down their processing lines without significant cost.  For example, jelly-bean like products can solidify in the piping if the production line is shutdown.  Even a failure to move products off the loading dock can cause a backup that causes a production line to shutdown, so the failure of a network connection to the shipping label printer can be catastrophic.

The last example above demonstrates how a single SLA is seldom possible or desirable.  Businesses may need to have multiple SLAs, one for each major facet of the business.



Re-posted with Permission 

NetCraftsmen would like to acknowledge Infoblox for their permission to re-post this article which originally appeared in the Applied Infrastructure blog under


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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.