# Nokia IXR Data Center Network How a Nokia data center network links racks of servers through leaf and spine switches, and how a message travels across them\. By clever\-otter\-e563a014 Topic: Computing, AI & Electronics [Open the interactive Jig](https://ask.jig.com/j/ZdE2bJ1PLzDp) ## Transcript ### 1. A room full of talking computers A data center is a big room full of computers called servers\. They talk to each other all the time, billions of times a second\. A network of switches and glass fibre cables makes that possible\. Let's see one built with Nokia switches\. Drag anywhere to look around the hall\. ### 2. Leaf switches: one on every rack Each tall cabinet, called a rack, holds many servers\. At the top sits a Nokia 7220 IXR\-D2L, a leaf switch\. Like a leaf on a branch, it is where the servers join the network\. A D2L has 48 server ports running at 25 gigabits per second each, in a box only 4\.4 cm tall\. ### 3. Spine switches: the crossroads Behind the racks stand the spine switches, two Nokia 7220 IXR\-D5s\. Every leaf has a cable to every spine, and leaves never cable to each other\. So any server can reach any other in the same few steps\. One D5 can move 12\.8 terabits per second through 32 ports of 400 gigabits each\. ### 4. The big one: Nokia 7250 IXR In the middle stands a Nokia 7250 IXR\-10, a modular switch\. Instead of fixed ports it has slots for line cards, which slide in and out like drawers\. It links this group of racks, called a pod, to other pods in the building\. The 7250 IXR\-10 is 13 rack units tall and has eight line\-card slots\. ### 5. A message takes the trip Watch a message travel from a server in the first rack to a server in the last\. It climbs to its leaf, crosses a spine, then drops down the other leaf into the server\. It passes through just three switches: leaf, spine, leaf\. Inside the fibre, the message really is a flash of light\. ### 6. Meet EDA: Event\-Driven Automation EDA is Nokia software that runs the whole network\. People tell it what they want, called the intent, like "connect these leaves and spines"\. EDA works out every switch's settings and sends them together\. If one switch cannot take its part, none of the changes stay, so the network is never left half\-built\. Amber flashes are EDA's messages\. Blue flashes are data\. ### 7. Something happens: EDA reacts Things happen in a network: a cable gets pulled, a part wears out\. The switches quickly send traffic another way, through the second spine\. EDA notices the event, raises an alarm and shows exactly which cable needs fixing\. That is why it is called event\-driven: it reacts to events as they happen\. ### 8. The whole fabric Leaves for the servers, spines as crossroads, a big 7250 IXR linking pods, and EDA keeping everything as intended\. Engineers call this mesh a fabric\. Your next video call or online game may travel through one just like it\. To grow the fabric, add more leaves and spines; EDA sets up the new switches the same way\.