Signaling and Media CSC 363 DePaul University 14 January, 1998

Review #1 Lhasa Labs currently employs 8 people but plans to add 10 more in the next four months. Users will be working on multiple projects, and only those users assigned to any one project should be permitted to access the project files. You’ve also been instructed to set up the network to make it easy to manage and back up. What kind of network (peer-to-peer, server, hybrid) would you choose and why?

Review #2 GJS Enterprises has hired you as a productivity consultant. Currently, they employ six people who routinely exchange information via sneakernet. They want the cheapest possible solution and only minimal training for employees. Individual employees also must be able to control resources on their own machines. Would you choose a peer-to- peer, a server-based, or a hybrid network? Why?

Review #3 American Tool and Die operates two machine shops, one in Towson, Maryland and the other in Beltsville, Maryland. The company wants to be able to share a single database between the two locations, so that managers at each facility can exchange work orders and monitor inventory on demand. Individual users need some control over individual resources, but they also want network faxing and dial-in services at each location. What type of network would you choose and why?

Review #4 From the case in #3, what kind of specialized servers will you need to install at American Tool and Die?

Transmission Your computer needs a file from the mainframe in the next room. How can that data be transmitted over a communications channel? –Encode the data –Modulate the data –Transmit the data

What do you know about signaling? Analog=> Digital=>

Analog Signaling AdvantagesDisadvantages

Digital Signaling AdvantagesDisadvantages

Digital Encoding Current State –Presence or absence of a state –Discrete voltages represent 0 and 1 State Transition –State change (hi- low/low-hi) represents data

Commonly-Used Encoding Schemes Bi-Polar Alternate Mark Inversion –Used by T-carriers –Reduces bandwidth required by half Unipolar Signal –+3 volts for 1, no volts for zero –Receiving equip. measures voltage once each bit time

Commonly-Used Encoding Schemes Manchester Differential Manchester

Bit Synchronization Why synchronize? Asynchronous=> Synchronous=> –Guaranteed state change –Separate clock signal –Oversampling

Broadband vs. Baseband BroadbandBaseband

Problem: You are asked to evaluate two new networking products for transmitting data over special coaxial cable. One product uses analog signaling, the other digital. Which will cost less and why? Which is more likely to provide greater bandwidth and why?

Cabled Media Check table on page 76

Problem: At GJ Corporation, a new network is being planned. The engineers in the design shop must be connected to the accountants and the sales people in the front office, but all routes between the two areas must traverse the shop floor, where arc welders and metal-stamping equipment create potent sources of EMI and RFI. Given that both the engineering and front office areas will use 10BaseT ethernet, how might you interconnect those two areas? What medium is guaranteed to be immune from such interference?

Solution Slide

Problem: The ABC Company occupies three floors in a 10-story building, where the elevator shaft provides the only path among all three. In addition, the users on the 10th and 11th floors must all access a collection of servers on the 9th floor. Explain what kind of connections would work in the elevator shaft. If more than one choice is possible, pick the best options and explain the reasons for your choice. Assuming that interfloor connections might someday need to run at significantly higher speeds, reevaluate your choice. What is the best type of medium for open-ended bandwidth needs? Explain.

Solution Slide

Wireless Media-Radio Transmission Systems How do they work? When would you use? Advantages and disadvantage

Microwave Transmission Systems How do they work? When would you use? Advantages and disadvantages?

Infrared Transmission Systems How do they work? When would you use? Advantages and disadvantages

Problem: You are the CIO of an interstate trucking company. You need to maintain constant contact with your fleet of trucks. Which wireless technologies will enable you to do this?

Problem You need to connect two buildings across a public road, and it is not feasible to use a direct cable connection. –When would you use a microwave link? –When would you use a radio link? –When would you use an infrared laser link?

Problem: You need to attach your computer to the cabled network. How do you do this?

Network Adapter Cards Encode Transceive=> Software drivers determine method of encoding and transmission

Configuring Network Adapters: IRQs and Ports PCI vs. ISA or EISA bus computers IRQ=>interrupt request--what signal will get the attention of the device at this port Port=>I/O address=>small part of upper memory used to send data back and forth to CPU. Addresses are specified in Hex and typically range from

Choosing an Adapter Type of network Type of media Type of bus

Problem: You have an Ethernet card and a sound card with a MIDI interface in your computer. You cannot reach the network. What, most likely, is the problem?