Module Three

High speed serial interface n defines the electrical

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High Speed Serial Interface n Defines the electrical and physical interfaces to be used by DTE/DCE n Operates and the Physical Layer (1) WAN Devices Routers – router opens packet and looks at either the MAC or IP address only forwards to the network that it is destined. Operates at Network Layer (3) Multiplexors - MUX enables more than one signal to be sent out over one physical circuit WAN Switches – multi-port network devices operate at the Data Link Layer (2). Typically switch Frame Relay, X.25 and SMDS Access Servers – provides dial in and dial out access connections to a network. Typically asynchronous. Modems – interprets digital and analog signals, transmits over voice grade telephone lines. Channel Service Unit (CSU)/Data Service Unit (DSU) – used to terminate the physical interface on a DTE device such as a terminal. Remote Access Technologies Provide remote user (employee, vendor, partner) access into the network while maintaining C.I.A. (Confidentiality, Integrity, Availability) Benefits of Remote Access: n Reducing costs by replacing dedicated network lines n Providing employees flexible work styles, Telecommuting n Building efficient ties with vendors, partners, suppliers and employees. Remote Access Types – Many common with WAN protocols. Asynchronous Dial up Access n How most people access Internet n Use existing public switched phone network to access ISP ISDN - Integrated Services Digital Network n Carries voice, data over telephone networks n Two Interface Types n BRI – Basic Rate Interface composed of two B channels and one D Channel n PRI – Primary Rate Interface composed of a single 64 KBps D channel plus 23(T1) or 30 (E1) channels xDSL - Digital Subscriber Line n Uses existing twisted pair telephone lines. Cable Modems n High speed access from the cable company n Users share the Coax connection n Throughput varies depending on number of users n Considered insecure because local segment is not filtered or firewalled (Says Who?) Wireless Technology n Fastest Growing area of connectivity n Encryption is being developed n 802.11a – 5 Ghz wireless - very soon
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n 802.11b – 2.4 Ghz currently most popular up to 11 MBps n 802.11g – 2.4 Ghz but faster than 802.11b n WEP – Wired Equivalency Protocol – up to 128-bit WEP n WAP - Wireless Access Point n SSID – Service Set Identifier – Network Name n Use encryption, VPN, treat as external connection, directional antenna Secure Remote Access Methods: Restricted Address n Filtering by source IP address n Node authentication not user authentication Caller ID n Caller ID checks incoming number against approved list n Very commonly used, hard to defeat n Hard to administer for traveling users Call Back n Caller supplies password or identifier and hangs up n System dials back number listed for the user n Hard to administer for traveling users Remote Identification and Authentication n Verify who is remotely communication.
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  • Fall '12
  • Hurst
  • IP address, Packet filtering

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