Module 4 - The Internet Layer

Question 1

What services are provided by the Internet Layer?

Answer 1

• Unique network addressing scheme to identify nodes (hosts or routers) globally
• Mechanisms for path determination
• End-to-End forwarding of datagrams

Question 2

What are the IP Address Types?

Answer 2

• Unicast: Single Device (host or router) intended as the receiver
• Anycast: Special case in which the same unicast address is assigned to multiple devices
• Multicast: Multiple hosts intended as receivers
• Broadcast: All hosts and routers connected to a subnet intended as receiver (IPv4 Only)

Note: IPv6 does not define broadcast addresses. Instead uses link-local multicast addressing

Question 3

Choosing a subnet prefix length

Answer 3

• Based on the number of hosts required in a given subnet
• round up to the next highest power of two, minus the two reserved addresses
• Resulting exponent is the required bit length of the host component

# Hosts Req: 10, 2^4-2 = 14. Hosts bits = 4
Prefix Length = 32-4 = /28

Question 4

What are the steps to implement router summarization?

Answer 4

1. Define the octet that will be manipulated by the summarization
2. identify the original network prefix
3. look to the left of the prefix line and identify the area where all of the addresses have the same bit pattern. Draw a line down that portion
4. Look between those two lines and ensure all possible bit patterns are contained between the two lines. If so, then the route summarization can occur at that prefix.