Chapter 2

1: What lower layer protocol are IS-IS packets encapsulated into?
A1: IS-IS packets are directly encapsulated into layer 2 frames. They are not encapsulated into any layer 3 protocol; IS-IS is a layer 3 protocol itself.
2: Explain why routing protocols send their update and hello packets to multicast addresses, rather than to broadcast addresses. Does it impact network performance in any way?
A2: Routing protocols transmit their packets to multicast addresses so the packets can be filtered by network hardware. If all routing protocol packets were sent to broadcast addresses, they would need to be examined and then discarded by every device attached to the network (that wasn't interested in this specific information), which can waste a ...

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