Read Chapter 15 in Stallings. Do problems: 15.2, 15.4, 15.7
1. Consider the arrangement of learning bridges shown in Figure 7.1. Assuming all are initially empty, give the forwarding tables for each of the bridges B1-B4 after the following transmissions:
Identify ports with the unique neighbor reached directly from that port; that is, the ports for B1 are to be labeled "A" and "B2".
2. Consider hosts X, Y,Z, W and learning bridges B1, B2, B3 with initially empty forwarding tables, as in Figure 7.2.
3. Given the extended LAN shown in Figure 7.3, indicate which ports are not selected by the spanning tree algorithm. Read about Spanning Tree algorithm in the text book Chapter 14, page 490.
Some of the material covered in last class is also available in PPT slides from this site. Look at the slides for chapter 3.
1. Using the example given in figure 1, give the VC tables for all the switches after each of the following connections is established. Assume that the sequence of connections is cumulative; that is, the first connection is still up when the second connection is established, and so on. Also assume that the VCI assignment always picks the lowest unused VCI on each link, starting with 0.
2. For the network given in figure 2, give the datagram forwarding table for each node. The links are labeled with relative costs; your tables should forward each packet via the lowest cost path to its destination.
3. Give an example of a working virtual circuit whose path traverses some link twice. Datagrams sent along this path should not, however, circulate indefinitely.
4. Propose a mechanism that virtual circuit switches might use so that if one switch loses all its state regarding connections, then a sender of packets along a path through that switch is informed of the failure.
HW5: 1 & 2. from page http://http://gaia.cs.umass.edu/kurose/ethernet/additional.htm answer questions 16 and 17 ( "In the IEEE 802.11 specification...")
3 & 4. Chapter 11, Problem 11.4, 11.5
HW4: 1. An IEEE 802.5 token ring has five stations and a total wire length of 230 m. How many bits of delay must the monitor insert into the ring? Do this for both 4 Mbps and 16 Mbps; use a propagation rate of 2.3 x 10^8 m/s.
2. For a 100-Mbps token ring network with a token rotation time of 200 Ás and that allows each station to transmit one 1-KB packet each time it possesses the token, calculate the maximum effective throughput rate than any one host can achieve. Do this problem for IEEE 802.5 ring , and FDDI.
3. Chapter 6, problem 6.14
4. Chapter 8, problem 8.2
HW3: 1. The 1982 Ethernet specification allowed between any two stations up 1500 m of coaxial cable, 1000 m of other point-to-point link cable, and two repeaters. Each station or repeater connects to a the coaxial cable via up to 50 m of "drop cable". Typical delays associated with each device are given below (where c=speed of light in a vacuum=3 x 10^8 m/s). What is the worst-case round-trip propagation delay, measured in bits due to the sources listed?
|Coaxial Cable||propagation speed .77c|
|Link/drop cable||propagation speed .65c|
|Repeaters||approximately 0.6 microseconds each|
|Trasceivers||approximately 0.2 microseconds each|
2. Suppose the round-trip propagation delay for Ethernet is 46.4 Ás. This yoields a minimum packet size of 512 bits (464 bits corresponding to propagation delay + 48 bits of jam signal).
a) What happens to the minimum packet size if the delay timeis held constant, and the signaling rate rises to 100 Mbps?
b) What are the drawbacks to so large a minimum packet size?
3. From http://gaia.cs.umass.edu/kurose/ethernet/additional.htm do Problem 15 in the PROBLEM section of the page (Suppose node A and B...).
4. What is the baud rate of the standard 10-Mbps 802.3 LAN?
HW 2: 1. Show NRZ, Manchester, and NRZI encodiings for the bit patter 10011111000100001. Assume that the NRZI signal starts out low.
2. Show 4B/5B encoding and the resulting NRZI signal for the following bit sequence
1110 0101 0000 0011
3. From the text book Chapter 2, problem 2.2
4. From the text book Chapter 2, problem 2.3.
For problems 3 and 4 calculate the efficiency of Miller and E-NRZ encodings.
There is a lot of material I present that is not covered in the required text but is available on the Web or in some of the books below. Class participation and attendance is very encouraged. You will never get an A in this class if you don't attend lectures on the regular basis.
Required Text: W. Stallings, "Local & Metropolitan Area Networks" Fifth Edition, Prentice Hall 1997 ; Errata File
- Larry Petersen & Bruce Davie, "Computer Networks, A System Approach", Morgan Kaufman
- Jim Kurose and Keith Ross, "Computer Networking, A top-down approach", Addison-Wesley
- W. Stallings, "Data and Computer Communication", Prentice Hall (lots of details)
- Andrew Tanenbaum, "Computer Networks", Prentice Hall (good comprehensive overview)
- Uyless Black, Computer Networks, Protocols, Standards, and Interfaces, Prentice Hall
- The Web:
- ATM Bookmarks and Tutorials
- Long list of ATM related sites
- Raj Jain's web site
- References to ATM and FDDI papers and books by a leading researcher
- Introduction to Distributed Queue Data Bus
- Brief description of DQDB technology
- DQDB Physical Layer
- High-level description of DQDB's Physical Layer
- Simulation study of DQDB
- Research Project of the Design and Implementation of a Distributed Queue Dual Bus Network
- Digital Technical Journal: FDDI
- A number of articles about FDDI from DTJ: vol 3. no. 2
- Fibre Channel Association