Branch Office Remote Access Technologies

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Topics. Remote Access StrategiesLeased LinesT1 ServicesISDNSatellite TechnologyOptical Submarine Networks. Spanning the Globe. Corporate offices span the globeThe size and number of employees varies at each officeRemote access must be easy for users and manageable for administrators. Remote

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Branch Office Remote Access Technologies

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1. Chapter 6 Branch Office Remote Access Technologies

2. Topics Remote Access Strategies Leased Lines T1 Services ISDN Satellite Technology Optical Submarine Networks

3. Spanning the Globe Corporate offices span the globe The size and number of employees varies at each office Remote access must be easy for users and manageable for administrators

4. Remote Access Considerations Security Number of Users per location Number of Users Connected Simultaneously Number of Hours per day connected Type of Access required. I.E. e-mail.ftp Access is continuous or intermittent

5. Security Considerations Limit the number of entry points into a network Monitor and control access to the computer network Examine audit records and security logs Require strong passwords Change passwords every 30 days

6. What Works at One Location, May Not Work Everywhere Due to Government Regulations – Technology might not be exportable from United States Right of Ways may not be available – may have to use wireless Equipment may not be available - Obsolete Technology

7. Leased Lines Permanent telephone connection between two points Organization ‘owns’ the leased line – not shared with anyone else Quality of service is assured Line access is assured Line is always active Fixed monthly fee Fees based on distance and speed of connection

8. Advantages of Leased Line Flexible level of connection based upon your business requirements Synchronous service where upstream and downstream speeds are the same Private network offers reduced security risks as it does not use the public network Service Level Agreement provides peace of mind Managed service

9. DTE and DCE A point-to-point connection has two pieces of Data Termination Equipment (DTE) at each end. I.E. computer, printer or terminal In between the DTE are two Data Communications Equipment (DCE), I.E. modem

10. Company access to POP Companies connect to branch offices, or use leased lines for Internet Access Point of Presence (POP) is an access point to the Internet Internet is an essential communication, collaboration, and marketing tool which users need 24/7 Leased lines offer greater security than public links

11. Firewalls on Leased Lines Increased threats of Internet misuse has prompted companies to add firewalls to private leased lines to filter traffic coming into their network The firewall filters traffic based on rules Can block several types of attacks Can monitor network traffic Can not protect against virus attacks

12. Multidrop Connection Splitting usage of a single dedicated line is called a multidrop connection. Many DTEs can share one line with only two DTEs conversing at a time Without a multidrop, the organization would require a separate dedicated line for each site

13. Multipoint Connection Large companies use a combination of multidrop and multipoint connections Multipoint connections has many point-to-point connections and multipoint connections integrated into one large network

14. T-Carrier General Specifications Digital – provides improved error performance Medium Independent – UTP, STP, COAX, Microwave, Satellite, Ir, optical fiber – not true for speeds greater than a T1 Full-Duplex – simultaneous 2 way traffic Symmetric – same amount of bandwidth in each direction Four Wire Trunk Device

15. T1 Leased line speeds vary from 64 Kbps to 45 Mbps T1 speed is 1.54 Mbps Can carry voice, data and multimedia traffic T1 can divide voice and data into different channels 24 channels Each channel is 64 Kbps – a company can buy single channels (a fractional T1)

16. T1 Devices The 24 channels of a T1 are managed by a Time Division Multiplexer (TDM) Each channel is divided into a time slot I.E. there might be 12 time slots for voice, 6 time slots for data, 6 time slots for video Requires a CSU/DSU T3 45 Mbps – also fractional T3

17. CSU The Channel Service Unit (CSU) is the demarcation point from the Telco and the customer CSU is the end point of the digital signal CSU converts customer data and voice signals into the format needed by the Telco for transmission Used by Telco for diagnostic loop back tests

18. DSU Converts data signals from other devices Often built into 1 device with CSU Converts data signals to the format required as input to CSU DSU converts signals from bridges, routers, and multiplexers to bipolar digital signals used by the T1 digital lines Not needed if voice only traffic CSU/DSU may be built into other devices I.E. multiplexers, routers and cards in a PBX

19. T1 Types

20. Other T-Carriers

21. Switched Bandwidth If high bandwidth is only required sporadically, switched bandwidth might fill the need If can be a combination of dedicated bandwidth and switched (dial on demand) A LAN is connected through an Etherswitch to the multiplexer so users can use the fractional T1 line

22. ISDN Integrated Services Digital Network Digital service over twister pair copper Supports three simultaneous separate conversations Largely replaced by xDSL and Cable Modem services

23. DSL Digital Subscriber Line (DSL) uses two wire copper to provide always on Internet Limitation – distance between Central Office and customer determines speed, distance can’t be greater than a few miles Speed – 144 Kbps – 6 Mbps

24. ISDN BRI ISDN Basic Rate Interface (BRI) supports two channels (B channels) to carry conversations from telephone, computer, fax, or other device – each channel 65 Kbps A D channel carries call setup information and signaling is carried, 16 Kbps

25. ISDN PRI Multiple BRIs combined into an IDSN Primary Rate Interface (PRI) Dedicate trunks used to connect corporate locations to the telco CO Can connect to a PBX, mainframe, LAN, WAN, multiplexers, ISDN controllers and video conferencing units 1.544 Mbps through T1, 23 B channels, 1 D channel for signaling, timing and diagnostic

26. ISDN Equipment A Network Termination Device (NTI) serves as the network interface for the BRI connection – provides physical and electrical termination functions A Terminal Adapter (TA) is required for PC access Devices that support IDSN directly are called Terminal Equipment (TE1) I.E. digital phones, digital faxes, and intergrated voice/data terminals

27. Benefits of ISDN PRI Reduce call setup time Reduce costs when compared to T1 leased line High-speed switched access to low-volume remote locations Use both local and interexchange carrier services Provides bandwidth on demand

28. PRI vs T1

33. Communication Servers Communication Servers also known as Access Servers or Network Access Servers connect users to internetworks over normal telephone lines Purpose: deliver to remote enterprise users internetwork-ready connections thru modems connected to serial telephone lines

34. Access Server Components Processor Cards: plug in cards with a CPU, memory and a serial RS-232 port, w/o these each remote control session would require a separate PC SNMP (Simple Network Management Protocol) is built into the circuitry to provide remote management Controllers: video, SCSI, EIDE, dual Ethernet, Serial, USB

35. Access Servers Services Terminal Service: provide terminal emulation I.E. 3270, UNIX rlogin Protocol Translation Service: conversion between remove user’s virtual terminal protocol to another virtual terminal protocol Telecommuting Service: PPP or SLIP Routing Service: provide dial-on-demain routing (DDR) over dial-up phone lines

36. Access Server Features An Access Server is a collection of independent servers, each process card can run an Intel based Operating System: I.E. Windows, Linux, Free BSD UNIX Processor cards are hot swappable Can host SQL databases, Web IIS servers, FTP access, firewall and proxy servers

37. Access Server Communication Features A digiboard is a serial card with multiple RS-232 ports to provide analog access T1 access card for high speed ISDN access card

38. Windows 2000 Terminal Services Microsoft applications run from a server Remote users run software through browser, a Citrix Metaframe Access server becomes a thin client-server farms. Each dual processor card can support as many as 200 (average) users Thin clients (Net PC’s) have no floppy or CD-ROM and possible no hard drive

39. Unguided Media Electromagnetic wave transmission might simply an installation, I.E. don’t have to dig up the street. Broadcast – omni-direction Line of Sight, 3 types Microwave, Infrared and Laser (blocked by structures, limited distance due to curvature of the earth) Spread Spectrum Technology

40. Radio Broadcast Radio broadcast is omni-directional, signals are broadcast in all directions to provide a wide coverage Cellular phones use this technology Not secure, easily tapped

41. Microwave Microwave transmission is considered a form of radio and uses a high frequency range Susceptible to interference, jamming, and eavesdropping Uses dish antenna, horn antenna and waveguides Can be a health hazard

42. Infrared and Laser Light based technologies that operate on low power levels Used in LANs because the only operated over a limited distance Infrared built into PC’s, Palm Pilots, Printers, Cellular Phones, Remote Controls

43. Spread Spectrum Technology Spread Spectrum Technology (SST) is used in LANs Resists jamming and hard to intercept, used in Military applications Frequency hopping is the easiest Spread Spectrum Technology to use Signals are spread over a very high frequency range, over 200 times the bandwidth of the original signal

44. Satellite Links Data can be transmitted via microwave over great distances via satellites Satellites are used for weather forecasting, television broadcast, Internet communications and GPS 3 orbit altitudes: Geostationary, Low Earth Orbit, Middle Earth Orbit Life expectancy of 7 to 15 years, Solar panels Launch costs $15 Million each VSAT – Very Small Aperture Terminal, Shell Installed them at over 5,000 Shell gas stations

45. Geostationary Satellites Used to transmit data and television signals Stationary in relation to a specific location on earth 22,238 miles above earth Data speeds up to 155 Mbps Propagation delay .25 to .50 seconds More than 100 communication satellites in orbit Most coverage of the earth, 1 satellite can see 40% of earth, 3 satellites can cover globe

46. Low Earth Orbit LEO satellites are in orbit at a constant altitude a few hundred miles from earth Travel in orbit at 17,000 miles per hour, so gravity won’t pull them down Data rates of 2.4 to 9.5 Kbps Used for mobile phones, PDA, automobile communication systems 400 to 1,000 miles from earth’s surface Lowest earth coverage, Iridium global phone uses 66 LEO satellites to cover the globe

47. Middle Earth Orbit MEO satellites are used for global wireless communication Orbit earth in 2-12 hours Orbit at 8,000 miles Data rates of 9.6 to 38.4 Kbps Use modest size antenna

48. Submarine Networking 1858 first transatlantic cable installed for telegraph transmissions, worked only 30 days, they used 2,000 volts for transmission Optical cable is used for voice, data and Internet using Wave Division Multiplexing, optically amplified repeaters are installed along the ocean 8.4 terabits per fiber pair Trans-Atlantic coax cable from 1920 still used Over 116,000 miles of fiber was recently laid to Europe from North America

49. Submarine Networking Since 1988 20 new digital optical Trans-Atlantic cables have been installed Scouting ships survey the ocean bottom with sonar to determine a route with a soft ocean bottom and no wrecks Anywhere the water is less than 1 mile deep they will use a plow to dig a trench to bury the cable in the sand to keep the cable safe from anchors and fishing nets

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