Problem 4. (5 pts) (Q13.0) Consider the following arrangement of three switches S1-S3, three hosts h1-h3 and one OpenFlow controller C.

Assume that the switches report packets to C only if they do not already have a forwarding-table entry for the packets destination. After each report, C installs a forwarding-table entry on the reporting switch for reaching the packets source address via the arrival port. At that point the switch floods the packet (as the destination must not have been known). If a switch can forward a packet without reporting to C, no new forwarding entries are installed.

Packets are now sent as follows:

• h1h2
• h2h1
• h1h3
• h3h1
• h2h3
• h3h2

At the end, what are the forwarding tables on S2?

Answer:

h1 h2 h3 S1 S2 -S3 h1 h2 h3 S1 S2 -S3