 This week, we saw that network sends packets through layers, interacts with its peers using protocols and using IP addresses. Now the next interesting thing is that on the network, how does the router actually manage to send IP addresses from one IP address to the other, which is basically the source to the destination. So that looks like a challenging thing to teach. So once again, there are multiple ways in which we can teach this and let's try the same approach that we took last time of looking at an analogy. So this time, we will look at the Mumbai's Dabbawala network as the analogy. First let's understand how do they route these dabbas from one place to the other so that people get their lunch on time and then we can go on to looking at how does it actually happen in a network. One famous network in Mumbai is the Dabbawalas. In this video, we will try to understand the concept of routing by observing how the Dabbawalas deliver tiffins over large distances and that took quite reliably. It starts in the kitchen. Meet Anupam. Once the tiffin is ready, Anupam calls the Dabbawala Mohan to pick up the Dabbah from his address. The Dabbawala takes the tiffin and leaves for picking Dabbahs from other nearby houses. In Mumbai, 200,000 such Dabbahs are delivered within 3 hours. Can you think of a way this could be done? Turns out there is one and that's what we'll see now. Anupam's tiffin and all other tiffins have a special code on the top. Let's call this Dabbakode. Anupam lives on the Hanuman Street in Vilepale. The code for this location is E-VLP. This tells the Dabbawala the source address of the Dabbah. Our Dabbawala Mohan takes this Dabbah to Vilepale station along with the others he collected. Anupam's tiffin has to reach the 12th floor on Excel towers in Kharkar. In Vilepale station, Anupam's tiffin is loaded along with others onto the local train. Mumbai local stops for only 14 seconds on a station. So that's pretty much what you can do in this short time. There is a part of the code on the Anupam's tiffin we still haven't talked about. The destination code. The destination code on Anupam's tiffin is 39EX12. The Dabbawalas in the train look at the first number which is 3 in this case and place Anupam's tiffin with others to be delivered in Kharkar. On reaching Kharkar, all these Dabbas are offloaded and collected by the next set of Dabbawalas. Here the Dabbawala number 9 Rishi looks at the second number with the destination code and takes all Dabbas that have the label 9. So Anupam's tiffin is now with Rishi who will now deliver to its destination based on the final part EX12 which refers to the 12th floor on Excel towers in Kharkar. And here we are. The Dabbawala has reached Sima on time. It's still 15 minutes to lunchtime so that's how the Dabbawala network works. Now it's time for some questions. Now that you have seen the animation of the Dabbawala network, here's a fun thing to do. Imagine that you are a Dabbaa and try to keep track of what all information is stuck on you when you are routed through the network. Imagine that you are going from the home to the office and vice versa. And how are you routed through the network? So try to identify what is the key piece of information that each Dabbawala has to keep track of in order to route you through the network. Once you have done that, then we will come back to see how does this routing happen in a network. Once you have done that, post your answers in the discussion forum and in the next week, we will come back and see how does this idea that you have learnt through the analogy actually manifest itself in a network.