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MET CS 535: Computer Networks

MIDTERM: October 28, 1999

Required Text: A. Tanenbaum, Computer Networks, 3rd edition: Prentice Hall

Homework 1: Tanenbaum, Chapter 1, Problems: 7,8,10,12,17,18,22,26

Homework 2: Tanenebaum, Chapter 2, Sections 2.1, 2.2, 2.6, Problems: 2, 5,6, 9, 46

Homework 3: Tanenbaum, Chapter 2, Sections 2.3-2.6, Problems: 4,22, 24

Homework 4: Tanenbaum, Chapter 3, Problems 2, 3, 10, 25

Homework 5: Tanenbaum, Chapter 3, Problems 12, 15, 20

Homework 6: Tanenbaum, Chapter 4, Problems 1, Read and answer the following questions:

2. Recall that with the CSMA/CD protocol, the adapter waits K*512 bit times after a collision, where K is drawn randomly. For K=100, how long does the adapter wait until returning to Step 2 for a 10 Mbps Ethernet? For a 100 Mbps Ethernet?

3.  Suppose nodes A and B are on the same 10 Mbps Ethernet segment, and the propagation delay between the two nodes is 225 bit times. Suppose node A begins transmitting a frame, and before it finishes station B begins transmitting a frame. Can A finish transmitting before it detects that B has transmitted? Why or why not? If the answer is yes, then A incorrectly believes that its frame was successfully transmitted without a collision.

Hint: Suppose at time t=0 bit times, A begins transmitting a frame. In the worst case, A transmits a minimum size frame of 512+64 bit times. So A would finish transmitting the frame at t=512+64 bit times. Thus the answer is no if B's signal reaches A before bit time t=512+64 bits. In the worst case, when does B's signal reach A?

Homework 7: Tanenbaum, Chapter 4, Problems 21, 26, 30, 32 (hint: interpret maximum efficiency to mean maximum achievable bandwidth)

Homework 8: Tanenbaum, Chapter 5, Problems 1, 2, 3, 4

Homework 9: Tanenbaum, Chapter 5.2, Problems 8, 9. Kurose and Ross.  From page Do problem 3.

Homework 10: Tanenbaum, Chapter 5.3,5.5, Problems 23, 26, 27, 28

Homework 11: Kurose, Problem 4 (if you did not do problem 3 in Homework 9).

Homework 12: Tanenbaum, Chapter 6, Problems 6, 13, 14, 23




Reference (chapters)


Overview of networks, layering, OSI reference model, TCP reference model, client/server model, peer-to-peer model Tanenbaum: 1


Physical layer: theory (Nyquist, Shannon, Fourier): transmission media: twisted pair, broadband, baseband, fiber optics

Notes on Transmission Media

Tanenbaum: 2.1-2.3


Wireless transmission, Telephone system, ISDN, ATM Tanenbaum: 2.3-2.6,


Data Link Layer: framing, bit stuffing, error detection and correcting codes, LAN frame formats, flow control. Examples of the Data link layers: HDLC, PPP, ATM Tanenbaum: 3.1-3.6


Medium Access Sublayer: ALOHA, CSMA/CD, WDMA, Wireless. IEEE 802.* standards. Bridges Tanenbaum: 4.1-4.4
    6 Network Layer. Routing algorithms: RIP, link-status broadcast and SPF, routers, congestion control, resource management Tanenbaum: 5.1-5.3


Internetworking: IP datagrams, addressing, fragmentation, best-effort delivery, time to live, gateways. ICMP, ARP, demultiplexing gateways

ATM: network layer in ATM



Transport layer: goals, function, addressing, connection setup and tear down, flow control, error control, congestion control Tanenbaum: 6.1-6.2,


UDP: ports, unreliability, lack of flow and congestion control; TCP: 3-way handshake, congestion control, slow-start, retransmit timers, urgent data, checksum

ATM AAL layer protocols



DNS: mapping names to addresses, name space, caching. MX records; Session layer:: purpose, etc; remote procedure call (RPC), registry, marshalling


RPC (continued): Presentation layer: purpose, data representation, ASN.1., Sun XDR, compression. Huffman encoding, run length encoding


Security, cryptography and authentication (DES & RSA), digital signature; Application layer: overview; Electronic mail: SMTP, X.500