Chapter 10
Remote 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
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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
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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
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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
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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
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Compatibility (protocol, LAN)
Applications (file transfer etc.)
Security (virus etc.)
Avoid lock of host PC
Mobile-aware OS Functions
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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 dialup 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
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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
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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
• E-mail
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 Cellular
Personal 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