chapter 10 remote access and wireless networking business issues logical & physical topology...
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Chapter 10Remote Access and Wireless
Networking
• Business Issues
• Logical & Physical Topology
• Technology: Hardware & Software, & Wireless
• Personnel Communication Services
Business Issues
• Needs
• Costs
• Functions
Business Needs
• Telecommuting or Small Office Home Office (SOHO)
• Mobile computing for field representatives
• Remote technical support for customers
Hidden Costs
• Communication carriers service costs
• Wiring & bandwidth
• Management problems
Functions
• Exchange e-mail
• Upload & download files
• Remote access application programs
• Share LAN-attached resources
Logical Topology
• Remote node or remote access– Full client/server application– Use remote hard drive
• Remote control– Keystrokes and screen image– Input or output device for local PC– Use local PC hard drive
Security Consideration
• Password and its management
• Intrusion response
• Partitioning of data
• Encryption
• Dial-back systems
• Authentication protocol
Token Authentication- Types
• Types– Token response
• Private identification number (client)
• Challenge number (server)
• Challenge response number (client)
– Time-synchronous authentication• Private identification number (client)
• Random authentication number (client)
• Random authentication number (server)
Token Authentication - Management
• Encrypt data, ID, & password between client and server
• Auditable for failed attempts
• Limited remote access (time & day)
• Interoperate authentication server & communication server
Physical Topology
• Wire or wireless
• Serial port of a LAN-attached PC
• Communication server
• LAN modem (dial-in server) with four to eight PC Card (PCMCIA) slots
Hardware
• Communication servers– Offer application– Serial ports, CPU(s), & network interface
card(s)
• Remote node servers (gateway)– Offer remote node connection service– Application servers offer application– Compatibility, LAN & WAN services, call
management issue
Software Types
• Remote node software
• Remote control software
• Mobile-aware OS
• Mobile-aware application
• Mobile middleware
Remote Node Software
• Consideration:– Protocols, modem, & client support– Management– Security
• Types: Windows NT RAS & NetWare Connect
• PPP clients work with different server NOS
Remote Control Software
• Guest (remote) & host (local)
• Consideration– Compatibility (protocol, LAN)– Applications (file transfer etc.)– Security (virus etc.)– Avoid lock of host PC
Mobile-aware OS Functions
• Auto-detection of multiple configurations
• Built-in multiprotocol remote node client
• Direct cable connection
• File transfer and file/directory synchronization
• Deferred printing
• Power management
• Infrared connection
Mobile-aware Applications Oracle Mobile Agents (Oracle-in-Motion)
• 50:1 performance increase• Client/agent/server architecture
– Message manager (client): tracking pending requests on various servers through LAN links or PPP-based dial-up links
– Message gateway(server): message holding station between message manager and intelligent agent on server to minimize overhead
– Agent event manager (intelligent agent on server): represents mobile client during entire processing on server to save bandwidth and transmission time
Mobile Middleware
• Function: consolidate multiple client application request into a single transmission
• Pros:– Flexibility– Performance
Improve Remote Software Performance
• V.34 modems
• ISDN services
• 16550 UARTs and matching serial port drivers
• Data compression software/hardware
• Communication software
• Compatibility
Mobile MIB
• Balance between bandwidth & information
• Information:– Current user location– Type and speed of connection device– Type of remote client or remote control
software– Battery power– Memory
Wireless
• Transmission technology– Spread spectrum transmission– Infrared transmission
• Standards– IEEE 802.11
• Mobil IP (client, home agent)
Spread Spectrum Transmission
• Frequency-hopping spread spectrum (FHSS)– Hops within the frequency range– Less interference– Good for mobile computing
• Direct-sequence spread spectrum (DSSS)– 10 bits to data message for id– Complexity, cost, overhead to processing id– superior throughput
Wireless WAN Service
• Circuit-switched analog cellular
• CDPD (Cellular digital packet data)
• Private packet radio
• Enchanced paging and two-way messaging
• ESMR (enhanced specialized mobile radio)
• Microcellular spread spectrum
• PCS (personal communications services)
Selection Criteria of WAN Services
• Content
• Geographic scope
• Amount of data
• Urgency
• Compatibility with LAN
CDPD
• Transaction processing and database queries• Pros:
– Fast call setup– Inexpensive for short messages
• Cons:– Limited availability– Expensive for large file transfers
Circuit-switched Cellular
• Large file transfers and faxes
• Pros:– Widely available– Reasonable price for longer transaction
• Cons:– Longer call setup time– Expensive for short message
Private Packet Radio
• Short bursty messages and e-mail
• Pros:– Wide area– Connect to e-mail system
• Cons:– Proprietary networks– Expensive for large file transfer
Enhanced Paging or Two-way Messaging
• Guaranteed delivery
• Return receipt
• McCaw Cellular
Enhanced Specialized Mobile Radio
• One or two way
• Voice, paging, or message
Microcell Spread spectrum
• Internet
Analog Cellular
• Modems support cellular transmission at both ends
• Cellular enhanced modem at mobile telephone switching office (MTSO)
• Advanced mobile phone service
• 800 MHz
Digital CellularPersonal Communications Services
• Personal phone number PPN
• Standards– Time division multiple access (TDMA)– Code division multiple access (CDMA)
• No modem
• Social impact and changes
Assignment
• Review chapters 8-10
• Read chapter 11
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