WANs and Remote Connectivity

1
WANs and Remote Connectivity

• Dean (3rd), Chp. 7

2
Overview

• Essentials
• Topologies
• Services
• Comparison of transmission speeds
• WAN implementation
• Remote connectivity
• VPNs

3
Essentials

• WANs, MANs, LANs, and PANs
• Not someones idea of a joke
• Each has standard
• WAN ITU-T recommendations E, I, and many others
• MAN IEEE 802.16
• LAN IEEE 802.2, 802.3, and 802.11
• PAN IEEE 802.15 (Bluetooth)
• WAN includes telecommunications technology
  (lighting bolt)
• Generally consider to include wide area and have
  heavy trafficthough not necessarily true

4
Topologies

• Bus
• Ring
• Star
• Mesh
• Tiered

5
Services

• PSTN
• X.25 and Frame Relay
• ISDN
• T-Carriers
• DSL
• Cable
• SONET

6
PSTN

• Public Switched Telephone Network or plain old
  telephone service (POTS)
• Mixed media building's twisted-pair, phone
  company's twisted-pair, fiber, microwave, and
  satellite
• Dial-up connection
• Max throughput 56 Kbps
• Modem

7
X.25 and Frame Relay

• X.25
• ITU standard for Physical, Data Link, and Network
  OSI layers that guarantees delivery
• Max throughput 2.048 Mbps
• Analog packet switching technology
• Frame relay
• Digital update of X.25
• ITU and ANSI standards for Data Link layer
• Does not guarantee delivery

8
ISDN

• Integrated Services Digital Network
• ITU standard for transmitting digital data over
  PSTN
• Combine voice and data service
• Connection either dial-up or "dedicated"

9
ISDN Channels and Service

• Channels
• Bearer channels (B-channel) for voice and data
• Data channel (D-channel) for control signal
• Base Rate Interface (BRI)
• Two 64 Kbps B-channels and one D-channel
• Max throughput of 128 Kbps
• Devices Network Termination 1 (NT1), terminal
  adapter (TA), digital phone or Ethernet NIC
• Primary Rate Interface (PRI)
• 23 B-channels and one D-channel
• Max throughput of 1.544 Mbps
• DevicesNT1, Network Termination 2 (NT2), TA,
  digital phone or Ethernet NIC

10
T-Carriers

• Phone company's main lines used to be called
  "trunk" linesanalog
• Now providers of dedicated lines are
  "T-carriers"digital
• Uses time division multiplexing
• T1 has 24 64Kbps channels or 1.544 Mbps
• T3 28 T1 672 channels and 44.736 Mbps
• T1 cost 2000 to 3000 per month
• Devices PBX or data switch, CSU/DSU with
  multiplexer, T-carrier

11
Levels of T-Carrier Service
12
DSL

• Digital subscriber line
• Can span only limited distanceADSL 18,000 ft.
• Uses advanced modulation techniques of inaudible
  frequencies (above 3300 Hz) to transmit digital
  data over regular (but clean) phone lines
• Devices Splitter, DSL modem, and standard phone
  or Ethernet NIC

13
Types of DSL

• Not shared throughput
• Types of DSL

14
Cable

• TV cable company's Internet service
• Fiber distribution
• Coax local drops
• Shared media
• 56 Mbps downstream and 10 Mbps upstream
• Customer 3 Mbps down and 1 Mbps up
• Devices cable modem and Ethernet NIC

15
Cable, DSL, Satellite URLs

• http//www.broadbandreports.com/prequal
• https//www.ibuybroadband.com/ibb2/consumer.asp
• https//www.ibuybroadband.com/ibb2/default.asp
• http//www.satelliteinsight.com/satellite-internet
  .html
• http//reviews.cnet.com/Broadband_power_search/400
  2-6549_7-5114723.html?tagcnetfd.dir
• http//partner.getconnected.com/123/v_internet/i_c
  ommon_geography.asp?caller/123/v_internet/i_plan_
  view.asp3Faffil3Dbbbuyer26

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SONET

• Synchronous Optical Network
• Developed by Bell in 1980's
• ANSI and ITU standards
• Interoperability used to aggregate T1 lines
• Underlying technology for ATM
• Uses timing scheme to transmit and receive data
• Over FDDI
• Optical Carrier levels Table 7-3, p. 372

17
Comparison

• Table 7-4, p.373

18
WAN Implementation

• Speed
• Reliability
• Security

19
Remote Connectivity

• Dial-up
• Routing and Remote Access Service (RRAS)
• Microsoft routing / firewall application for
  Sever 2003
• Authentication and communication services
• Serial Line Internet Protocol (SLIP) and
  Point-to-point Protocol (PPP)
• Client applications for remote access
• Data Link layer protocols
• SLIP earlier and simpler protocol PPP more
  versatile
• Remote control
• Take over control of remote terminal
• pcAnywhere or XP's Remote Desktop
• Terminal services
• Early apps provided remote access to LAN/server,
  such as SSH, Telnet
• Now offer wider range of services, such as Citrix
• Web portals
• Secure Web-based access to services
• Novell's Management Portal, LOUIE, WebCT,
  shopping carts

20
Virtual Private Network (VPN)

• Uses "public" (Internet) network for "private"
  connection
• Maintain privacy by using
• Tunneling protocolsencryption of data to form a
  "tunnel" through InternetIPSec
• Security proceduresauthentication, such as
  passwords, and use of path known and acceptable
  to VPN administrator
• Trusted VPN use only paths controlled by trusted
  service provider only traffic allowed by
  provider can use path
• Secure VPN use encrypted data to form tunnel,
  uses security procedures, and acceptable path
• Hybrid Encrypted data over trusted paths
• Source http//www.vpnc.org/vpn-technologies.html

21
Secure VPN Standards

• IPsec with encryption in either tunnel and
  transport modes. The security associations can be
  set up either manually or using IKE with either
  certificates or preshared secrets. IPsec is
  described in many RFCs, including 2401, 2406,
  2407, 2408, and 2409.
• IPsec inside of L2TP (as described in RFC 3193)
  has significant deployment for client-server
  remote access secure VPNs.
• SSL 3.0 or TLS with encryption. TLS is described
  in RFC 2246. An excellent book on SSL 3.0 and TLS
  is "SSL and TLS Designing and Building Secure
  Systems" by Eric Rescorla (ISBN 0201615983).
• IPSec IP Secure L2TP Layer 2 Tunneling
  Protocol SSL Secure Socket Layer TLS Transport
  Layer Security
• Source http//www.vpnc.org/vpn-technologies.html

22
Trusted VPN Technologies

• Technologies for trusted layer 2 VPNs include
• ATM circuits
• Frame relay circuits
• Transport of layer 2 frames over MPLS, as
  described in draft-martini-l2circuittrans-mpls
  and other related Internet Drafts.
• Technologies for trusted layer 3 VPNs include
• MPLS with constrained distribution of routing
  information through BGP, as described in
  draft-ietf-ppvpn-rfc2547bis and other related
  Internet Drafts.
• Multiprotocol Label Switching labels IP
  datagrams with special information routed using
  label information
• Border Gateway Protocol for routing
• Source http//www.vpnc.org/vpn-technologies.html

23
Summary

• Wide area networks use telephone and competing
  technologies
• Tend to cover extended distances (miles)
• Use either
• Point-to-point dedicated media
• Point-to-multipoint broadcast media
• Predominate services
• ISDNbusiness and some individuals
• DSL or cablesmall businesses, organizations, and
  individuals
• X.25 / frame relayprivate WANs
• T-carriersbusiness and organizations
• SONETservice providers