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Week 2 worksheet — Devices and topologies

Name Date

1 — Dedicated links

Observe:

Value
# of dedicated links for 3 nodes
# of interfaces required on each node
# of IP addresses required on each node
# of links required to connect 4, 5, and 10 nodes
Can H2 hear the conversation between H1 and H3

2 — Hub vs switch

Predict: If you listen on PC3's cable:

  1. Can you hear the conversation between PC1 and PC2? ______
  2. Same question, but with a switch in place of the hub. ______
  3. Which layer does a hub operate at? ______
  4. Which layer does a switch operate at? _____
  5. Which topology does a hub implement? ______
  6. Which topology does a switch implement? ______

Observe:: mark with a what PC3 sees after the first ping from PC1 to PC2

ping on a hub ping on a switch
ARP request on PC3's wire
ARP reply on PC3's wire
ICMP request on PC3's wire
ICMP reply on PC3's wire

In one sentence: what does the switch know after the first ping from PC1 to PC2 that it did not know before?

3 — Two legs in two networks

Predict:

  • What does a node need to know before it can send a packet to another network? ______
  • What is the minimum number of networks a router belongs to? ______

Observe:

Whose address? (answer with PC1, PC2 or RTR)

PC1 capture PC2 capture
ICMP source IP address
ICMP source MAC address
ICMP destination IP address
ICMP destination MAC adress

One sentence: does RTR IP addresses appear in any of the two captures at all? If so, for what purpose?