N adsl asymmetric digital subscriber line more

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n ADSL – Asymmetric Digital Subscriber Line more bandwidth downstream from 1.5 to 9 MBps with upstream 16 to 640 KBps. ADSL works at 18,000 feet lengths, theoretical and 14,400 practical over single copper twisted pair. n SDSL - Single-line (Symmetric) Digital Subscriber Line provides from 144 KBps up to 1.544 MBps both down and up, depending on distance, over single copper twisted pair, works at 10,000 feet lengths. n HDSL – High-Rate Digital Subscriber Line - 1.544 MBps both down and up over two copper twisted pair. Provides T1 speeds. Can do 2.048 MBps on three copper twisted pair. n VDSL – Very-high Rate Digital Subscriber Line – 13-52 MBps down and 1.5 MB to 2.3 MBps upstream over single copper twisted pair operating range 1,000 – 4,500 feet Circuit Switched vs. Packet Switched Circuit Switched n Defined as a switching system in which a physical circuit path must exist for the duration of the transmission n Physical permanent connections from one point to another n Older technology than Packet Switching n Phone companies use this a lot Packet Switched n Create virtual circuits used as needed and reduce cost. n Defined as a switching system where nodes share bandwidth by sending small packets. n Each packet sent to the next destination by the router. n Packets reassembled based on original sequence
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Message switching – Message sent from node to node and stored at each node until forwarding path is available Packet Switching Technologies – X.25, Link Access Procedure Balance (LABP), Frame Relay, Switched Multimegabit Data Service (SMDS), Asynchronous Transfer Mode (ATM), Voice over IP (VoIP) X.25 n First packet switching network n Supports Switched Virtual Circuits (SVCs) and Permanent Virtual Circuits (PVCs) n Designed to operate effectively regardless of the type of systems connected to n Currently much more predominant overseas than in the US Link Access Procedure Balance (LAPB) n Designed for use with X.25 n Defines frame types n Can retransmit, exchange and detect out of sequence frames or missing frames. Frame Relay n High performance WAN protocol n Operates at Physical and Data Link Layers (1 and 2) n Originally designed for ISDN n Replaces X.25 and LAPB n Simple and fast, no error correcting n Supports Switched Virtual Circuits (SVCs) and Permanent Virtual Circuits (PVCs) n Not available everywhere Switched Multimegabit Data Service (SMDS) n High Speed over public switched networks n Connectionless bandwidth on demand Asynchronous Transfer Mode (ATM) n High bandwidth, low delay n Uses switching and multiplexing n Uses 53 byte fixed size cells instead of frames n Can allocate bandwidth on demand n Taking place of FDDI in Campus Backbone Voice Over IP n Combines media types (voice, video, data, audio) into one IP packet n Provides benefits in cost, performance and interoperability n Very new but far reaching potential Other Important WAN Protocols Synchronous Data Link Control (SDLC) n Uses polling access method for mainframes n Based on dedicated leased line n Evolved into HDLC and LAPB n Operates at Data Link Layer (2) High-Level Data Link Control (HDLC) n Derived from SDLC n Specifies data encapsulation method on synchronous serial links n Operates at Data Link Layer (2)
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  • Fall '12
  • Hurst
  • IP address, Packet filtering

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