Routing and Switching
Routes
Routes are the backbone for most of the internet. It is a system of costs that help manage where traffic is supposed to go. Even for many in computers, the whole internet itself seems like a hard target. This is an illusion.
All it takes is for one computer to have a bad route or not be on the same page to mess up things. As one of my teachers put it, Pakistan made the mistake of blacklisting Youtube by black holing the domain. This works, but if you set the "cost" too low and your computers share that route with the whole world, suddenly the whole world tries to go through Pakistan to get to Youtube because the cost is low. Youtube is of course blacklisted in Pakistan.
- Syntax for routes on a Cisco Router: ip route [Incoming IP] [Incoming Subnet] [Outgoing Interface] [Next Hop Address] [Distance/Cost]
| IP | MASK | OUTGOING | NEXT HOP | COST |
|---|---|---|---|---|
| Example | Example | Example | ||
| Example | Example | Example | ||
| Example | Example | Example | ||
| 0.0.0.0 | 0.0.0.0 | 10.19.114.1 | 10.19.114.81 | 35 |
| 10.19.114.0 | 255.255.255.0 | On-link | 10.19.114.81 | 291 |
| 10.19.114.81 | 255.255.255.255 | On-link | 10.19.114.81 | 291 |
| 10.19.114.255 | 255.255.255.255 | On-link | 10.19.114.81 | 291 |
| 127.0.0.0 | 255.0.0.0 | On-link | 127.0.0.1 | 331 |
| 127.0.0.1 | 255.255.255.255 | On-link | 127.0.0.1 | 331 |
| 127.255.255.255 | 255.255.255.255 | On-link | 127.0.0.1 | 331 |
| 192.168.56.0 | 255.255.255.0 | On-link | 192.168.56.1 | 281 |
| 192.168.56.1 | 255.255.255.255 | On-link | 192.168.56.1 | 281 |
| 192.168.56.255 | 255.255.255.255 | On-link | 192.168.56.1 | 281 |