CS457/557 & MIS420/520 - Remote Access and Wireless Networking

OBJECTIVES

Understand the difference between and proper application of remote node vs. remote control computing.
Understand the business motivation behind the need for remote access network design.
Understand the importance of and networking implication of mobile computing.
Understand how to sucessfully design logical and physical topologies fpr remote access networks, including wireless LAN and WAN services.
Understand how to evaluate remote access technology, including hardware, softwaare, and WAN services.
Understand the unique security issues introduced by remote access and mobile computing.

Business Issues of Remote Access
- telecommuting [SOHO - Small Office Home Office]
- mobile computing [field reps]
- technical support [remote diagnostics]
The Hidden Costs of Telecommuting
- long-distance charges
- additional wiring from street to home / additional phone lines
- need to sort personal calls from business calls
- requires more expensive lines (ISDN, ADSL)
- applications may run slower

Needs analysis
- exchange e-mail
- upload/download files
- run interactive applications remotely
- utilize LAN-attached resources

Remote Node vs. Remote Control

Functional Characteristic	Remote Node	Remote Control
Also called	Remote Client Remote LAN Node	Modem remote control
Redirector hardware/software required?	Yes	No
Traffic characteristics	All client/server traffic	Keystrokes and screen images
Application processing	On the remote PC	On the LAN-attached local PC
Relative Speed	Slower	Faster
Logical role of WAN link	Extends connection to NIC	Extends keyboard and monitor cables
Best use	With specially written remote client applications that have been optimized for execution over limited-bandwidth WAN links	DOS applications; graphics on Windows apps can make response time unacceptable

Protocols and Compatibility [Figure 10.3]
- remote control - uses proprietary protocols
- remote node - often uses TCP/IP (protocol stack) and PPP (data-link layer WAN protocol)
Security
- Password assignment and management
- Intrusion responses
- Logical/physical partitioning of data
- Encryption
- Dial-back systems
- Remote client software authentication protocols

Physical Design Issues
[Figure 10-5]
- serial-port of a LAN-attached PC
- Communications server
- LAN modem

Hardware
- Communications Services and Remote Access Servers (Access servers - Remote access servers - Remote node servers - Telecommuting servers - Network resource servers - Modem servers - Asynchronous communications servers) - Figure 10-6
- Wireless LANs (IEEE 802.11 - uses CSMA/CA)
  - Spread spectrum transmission - uses a range of frequencies
  - Infrared transmission
Software
- Remote Control Software (takes over remote control of the host)
  PCAnywhere; Carbon Copy
  - avoids lockup of host PC
  - allows guest PC to disable keyboard/monitor of host
  - adds security to prevent unauthorized access
  - virus detection
- Remote Node Software
  Windows NT RAS; NetWare Connect
- Mobile-Aware OSs - Win 95/98
  - Stand-alone computing on a laptop
  - Remote node/remote control computing to corporate headquarters
  - Synchronization of files / directories with desktop workstations at home or office
- Mobile-Aware Applications (Oracle Mobile Agents)
- Mobile Middleware (APIs) [Figure 10-15]
Management and Configuration of Remote Access Technology
- Use V.90 modems
- Use ISDN or ADSL services
- Use 16550 UARTs
- Use data compression hardware/software
- Use screen caching
- Use network(LAN) caching