Yesterday we had thought provoking discussion on “How to Calculate Network Availability in below given scenario?” in our SIAM Expert Whatsapp group where we have 200+ experts..
Thought of sharing same with all of you…
Consider below Scenario and let me know is it fairly simple or tricky to calculate Network Availability SLA ?
1.NovelVista has several remote offices with their own Internet connection.
2.Each office connects back to the headquarters-HQ’s via a VPN tunnel.
3.Users at each remote office need to access a mix of internal applications
across the VPN tunnel and external services via the local Internet connection.
Here is my Question
1.What will be network availability value formula if the VPN tunnel is down, but not the Internet connection?
2.Will this availability value calculation formula change if the Internet connection goes down?
We discussed this, brainstormed and got amazing answers… Here is summary of discussion
In normal situation we will calculate network availability based on the uptime of the Internet connection, because if the Internet goes down, it will affect both internal and external applications. But on other side in reality - a failure of the VPN tunnel would still impact the access to internal applications but not external applications (partial outage).
1.Both VPN and internet will have its own availability measures different technology even if they are network related. Best would be to divide and measure them.
2.E2E business KPI's is what customers are looking at.. as we have business processes.. we have to link infrastructure and software components associated and measure business KPI's rather than SLA
3.One of approach to calculate network availability can be weighted average between the availability of the Internet connection and the availability of the VPN tunnel: Network Network Availability = Weight external_apps x Network Availability Internet + Weight Internal_apps x Network Availability VPN
4.The two weights values should be set and discussed with the business architect considering business criticalness.
5.For example, let’s assume that 80% of the business applications used by the users are external (Internet) and that the remaining 20% are internal (VPN). If in one-year time interval, the Internet connection never failed, while the VPN tunnel was unavailable for 1 day, then the value of the overall network availability for that location is:
6.Network Availability = 80% * 100% + 20% * (99.726%) = 99.945%
So what you expert think about this? write your thoughts and concerns inthe comment section
Any guidance would be appreciated
Posted: Fri Aug 24, 2018 12:07 am Post subject: think about services not infrastructure
Network availability as such has no meanings to me ... Network is a set of hardware and software components that are assembled to provide some services. What SLAs should measure is availability of services.
as such, in your scenario, I understand that "network" is contributing to 2 different services
- internet service: providing access to the outside world and resources , and possibly, allowing the outside world to exchange with you.
- internal (intranet) services: providing access to the internal world to allow users ans systems to communicate ans exchange information internally.
I would consider having one SLA for each service. If that has any meaning, calculate an average or, better, a weighted average depending on the criticality of each service for the operations of the company.
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