Routing and Switching: Difference between revisions

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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.  
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.  


*ip route [Incoming IP] [Incoming Subnet] [Outgoing Interface] [Next Hop Address] [Distance/Cost]
*Syntax for routes on a Cisco Router: ip route [Incoming IP] [Incoming Subnet] [Outgoing Interface] [Next Hop Address] [Distance/Cost]


<code><nowiki>
 
          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
{| class="wikitable" style="margin:auto"
    10.19.114.81 255.255.255.255         On-link      10.19.114.81   291
|+ A Simple Routing Table From An End Device
    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
! IP || MASK || NEXT HOP || COST
        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
| 0.0.0.0 || 0.0.0.0 || 10.19.114.81 || 35
    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
|10.19.114.0 || 255.255.255.0 || 10.19.114.81 || 291
  192.168.56.255  255.255.255.255         On-link      192.168.56.1   281
|-
    192.168.126.0    255.255.255.0        On-link    192.168.126.1    291
|10.19.114.81 || 255.255.255.255 || 10.19.114.81 || 291
    192.168.126.1  255.255.255.255        On-link    192.168.126.1    291
|-
  192.168.126.255  255.255.255.255        On-link    192.168.126.1    291
|10.19.114.255 || 255.255.255.255 || 10.19.114.81 || 291
    192.168.154.0    255.255.255.0        On-link    192.168.154.1    291
|-
    192.168.154.1  255.255.255.255        On-link    192.168.154.1    291
|127.0.0.0 || 255.0.0.0 || 127.0.0.1 || 331
  192.168.154.255  255.255.255.255        On-link    192.168.154.1    291
|-
        224.0.0.0        240.0.0.0        On-link        127.0.0.1    331
|127.0.0.1 || 255.255.255.255 || 127.0.0.1 || 331
        224.0.0.0        240.0.0.0        On-link      192.168.56.1    281
|-
        224.0.0.0        240.0.0.0        On-link    192.168.126.1    291
|127.255.255.255 || 255.255.255.255 || 127.0.0.1 || 331
        224.0.0.0        240.0.0.0        On-link    192.168.154.1    291
|-
        224.0.0.0        240.0.0.0        On-link      10.19.114.81    291
|192.168.56.0 || 255.255.255.0 || 192.168.56.1 || 281
  255.255.255.255  255.255.255.255        On-link        127.0.0.1    331
|-
  255.255.255.255  255.255.255.255        On-link      192.168.56.1   281
|192.168.56.1 || 255.255.255.255 || 192.168.56.1 || 281
  255.255.255.255  255.255.255.255        On-link    192.168.126.1    291
|-
  255.255.255.255  255.255.255.255        On-link    192.168.154.1    291
|192.168.56.255 || 255.255.255.255 || 192.168.56.1 || 281
  255.255.255.255  255.255.255.255        On-link      10.19.114.81    291
|}
</nowiki></code>

Latest revision as of 04:47, 28 July 2024

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]


A Simple Routing Table From An End Device
IP MASK NEXT HOP COST
0.0.0.0 0.0.0.0 10.19.114.81 35
10.19.114.0 255.255.255.0 10.19.114.81 291
10.19.114.81 255.255.255.255 10.19.114.81 291
10.19.114.255 255.255.255.255 10.19.114.81 291
127.0.0.0 255.0.0.0 127.0.0.1 331
127.0.0.1 255.255.255.255 127.0.0.1 331
127.255.255.255 255.255.255.255 127.0.0.1 331
192.168.56.0 255.255.255.0 192.168.56.1 281
192.168.56.1 255.255.255.255 192.168.56.1 281
192.168.56.255 255.255.255.255 192.168.56.1 281