IS-IS Levels
IS-IS - Defined how levels traffic flow through network.
Defining Communication Levels:
Level 0
End User is connected to a Default gateway Router/L3 Switch this is consider to be a Level 0 communication
Level 1
When a Intermediate System (IS) route packets to another Intermediate System (IS)
Here is another example; routers routing packets within the same autonomous system
Level 2
Level 2 is when router is sending packets to a different autonomous system
