N adsl asymmetric digital subscriber line more

Info icon This preview shows pages 18–20. Sign up to view the full content.

View Full Document Right Arrow Icon
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
Image of page 18

Info icon This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
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)
Image of page 19
Image of page 20
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern