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

• 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 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