Explain like I'm five · Network

What is SDN/NFV?

SDN and NFV, told as a story about a control tower that reroutes every post office's road at once, in software.

rerouting means visiting all three post offices and rewiring each by handeach post office has its route board nailed to the wall

Rerouting means fixing each post office by hand.The route board is nailed to the wall, so changing it is a hassle.

adding a feature means buying a new machine firsthardware is bolted to one spot — every change costs time and money

Every new feature means buying another dedicated machine.Hardware bolted to one spot makes every change cost time and money.

Office AOffice BOffice CControl TowerSDN = one control tower reroutes every road at once, in softwareNFV = swap the dedicated machine for software on a generic truck

The tower reroutes every road at once, in software.NFV swaps the dedicated machine for software on a generic truck.

Centralized controlone tower decides every road
Software-defined routinga software command changes the route
Functions as software (NFV)the function runs without a dedicated machine
Scale up or down fastgrow or shrink functions when needed
Control plane — the tower (software)decides every post office's routeData plane — the real post offices actually carrying parcels

The tower (control) and the field post offices (data) are kept separate.The control plane decides the route; the data plane actually carries the parcels.

features get added in software, with no new machineif the tower goes down, no post office gets new routesrerouting is fast and flexible — but if the tower stops, the whole network gets no new routes

If the tower's software fails, the whole network feels it.Rerouting is fast and flexible — but if the tower stops, the whole network gets no new routes.

In one breath

SDN is a tower rerouting every road at once, in software; NFV is installing a function as software on generic hardware instead of a dedicated machine.

SDN (Software-Defined Networking) separates the control plane from the data plane, letting one central controller govern a network's paths and policy entirely in software. NFV (Network Functions Virtualization) turns the function of dedicated network hardware — routers, firewalls — into software (VNFs) running on generic servers. Used together, they make a network fast and flexible to reconfigure.

When grown-ups say it

SDN
A tower that reroutes roads in software. Separates control from the field.
NFV
Installing a function on a generic truck instead of a dedicated machine. Turns a dedicated hardware function into software.
Control plane
The layer where the tower makes decisions. Doesn't carry anything itself.
Data plane
The real post offices that actually carry the parcels. Simply executes what the tower decides.
Virtual Network Function
A software function installed on a generic truck. Even a firewall or sorter can run this way.
5G Private Network
A delivery network dedicated to one factory. A private network can change its roads and functions in software too. → a delivery network just for one factory
Network slicing
Splitting one road into lanes by purpose. Another use of software-defined roads. → splitting the road into lanes
Firewall
A wall with many doors. A device often virtualized by NFV. → the wall with many doors
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