Midterm Exam #2 Review• Exam time is July 5th during class time.• The second homework and lecture content after

first mid-exam until this class will be covered.• You need to compute out the final numerical

results in your answer. Do not simply write down the formula as your answer.– You can bring a calculator (no computer, iPhone, etc)

Question Types– Knowledge questions

– True or false statement (explain why)

– Protocol

– Calculations

Knowledge Question Examples

• Compare pros and cons for go-back-N and selective repeat ARQ?– Go-back-N: pro: single timer, simple con: not efficient,

waste bandwidth when a packet is lost/broken– Selective repeat: pro: efficient, only lost/broken

packets need retransmission con: complicated with multiple timers, receiver needs a buffer to buffer out-of-order packets

• Difference between “Ethernet hub” and “Ethernet switch”?

• IPv6 uses how many bits for addresses?

Knowledge Question Examples

• Difference between Ethernet switch and router?• What is VLAN? Its advantages?• Interpret IP address block “a.b.c.d/n”? How

many IPs in it? First address? Last address?• What is NAT? Its pros and cons?• How many bytes are used for MAC address? IP

address? IPv6 address?• What are the three blocks of private IP subnets?• What is the minimum Hamming distance?

Protocol Example

• Stop-and-wait ARQ for noisy channel (hw2, Q9)• CRC circuit design (homework 2)• Bit stuffing and byte stuffing (ch11, homework 2)

Calculation Problem Examples

• Hamming Distance (ch10, Page 17-20)• Checksum (ch10, homework 2)• Go-back-N utilization compute (ch11.ppt, Page 34-37)• IP block subnet allocation (ch19.ppt, Page 34-40)• NAT table and address translation (ch19.ppt, Page 44)

• All questions in homework 2 will be covered

Midterm 2 Grade Statistics