
   
   
   Here are some useful terms for your everyday internet conversations...
   
   

ATM:  Asynchronous Transfer Mode.  A communications protocol which is
        defined for high speed data communications of 155Mb/s and higher.
        Commonly used with optical fiber connections.  Can also be run on
        wire, although this is less common.

Channel Bank: A device which splits a T1 line into 24 voice or digital
        circuits.

CIR:  Committed Information Rate. Used with Frame Relay connections to
        specify the minimum guaranteed throughput of a PVC.

DCE:    Data Communications Equipment.  The devices and connections of a
        communications network which connect the data communications channel
        with the end device (DTE).  Can be used to describe a CSU/DSU, a
        TSU or an ordinary modem.

DNS:  Domain Name Service. A protocol which provides an internet-wide
        database of host and domain names.  DNS is used to find the IP
        address of a host name given in the "host.com" notation.  Reverse
        DNS is used to find the host name given an IP address.

DS0:  Digital Signal level 0.  Also known as T1.  Bit rate is 1.544Mb/s with
        equivalent bandwidth of approximately 25 56Kb Lines.  Capable of
        serving a minimum of 50 modems at 28.8kb or 100 modems at 14.4Kb.

        T1 circuits are also used for voice telephone connections.  A single
        T1 line carries 24 telephone connections with 24 telephone numbers.
        When used for voice telephones, a T1 connection must be split into
        24 separate circuits by a Channel Bank (see above).

DS3:    Digital Signal level 3.  Also known as T3.  Equivalent in bandwidth
        to 28 T1's.  The bit rate is 44.736 Mbps.

DSU:    Data Service Unit.  Provides a DTE with access to digital telecommun-
        ications facilitites.

DTE:    Data Terminal Equipment.  Originally applied to dumb terminals which
        were connected to modems, DTE now refers to the 'computer' or other
        device to which a modem is connected to on the local side.  In
        Internetworking, DTE's are used to describe routers, terminal servers
        and computers.

Fractional T1:
        A unit of bandwidth which is some portion, but not all, of a
        standard T1 circuit.  Orderable in units of 64kb/s, typical
        increments are 64Kb, 128kb, 256kb, 512kb, 768kb, etc..

Frame Relay: A communications protocol which is somewhat related to X.25.
        Frame relay provides private virtual circuit (PVC) connections
        between networked nodes.

OC-N:   The optical signal that results from an optical conversion of an STS-
N
        signal.

SONET:        Synchronous Optical NETwork.  An ANSI/CCITT standard for standa
rdizing
        the use of optical communication systems.

STS-N:        Synchronous Transport Signal level n, where n = 1,3,9,12,18,24,
36,48.
        STS-1 is the basic logical building block signal for SONET with a
        rate of 51.84 Mbps.  STS-N are obtained by byte interleaving N STS-1
        signals together with a rate of N times 51.84 Mbps.

T1:   See DS0

T3:   See DS3

TSU:  Terminal Service Unit.  A high speed modem typically used with DS0
        (T1) circuts.  Also used in Fractional T1 applications.

   
   
   Please let us know if you have anything we should add. Send email to
   [IMAGE] Back to MegaNet Home Page
   
   Last updated on Thursday, 09-Mar-95 10:59:32 MST / 1,849
   by webmaster@mega.net
