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CSU/DSU

Discussion in 'Networks' started by grim, Nov 21, 2008.

  1. grim

    grim Gigabyte Poster

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    A lot of networking material always talk about CSU/DSUs.

    The thing is they never actually mention anything in detail. From what i can find is they sit between the WAN connection and the modem and they filter the signal from each side for T-carriers.

    I assume these are for T-carriers only and are an american thing. Do we need them on E-carriers ?

    Are they sort of the similar to having filters on ADSL connections ?

    GRim
     
    Certifications: Bsc, 70-270, 70-290, 70-291, 70-293, 70-294, 70-298, 70-299, 70-620, 70-649, 70-680
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  2. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    CSU/DSU is an North American thing and is tied into their T1/T3 system.

    Europe doesn't have those.

    Generally ISDN in EU uses a TA (terminal adaptor) for ISDN2.

    Harry.
     
    Certifications: ECDL A+ Network+ i-Net+
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  3. derkit

    derkit Gigabyte Poster

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    I knew the answer to that - only because I revised it tonight - glad to see something is settling in my mind!

    Even though OC-x run on fibres, do they use a CSU/DSU upon entry into a site?
     
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  4. grim

    grim Gigabyte Poster

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    No ones actually added to my thread :confused2

    GRim
     
    Certifications: Bsc, 70-270, 70-290, 70-291, 70-293, 70-294, 70-298, 70-299, 70-620, 70-649, 70-680
    WIP: 70-646, 70-640
  5. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    Partially true! :ohmy

    You can think of these units as the equivalent of a modem. The T1 is connected to one side, and a router connected to the other side.

    In the UK leased lines are usually variations of DSL, and a special DSL modem/router is supplied (I've got one of these somewhere left over from when I had a leased-line installed). These tend to be called NTU (Network Termination Unit).

    Harry.
     
    Certifications: ECDL A+ Network+ i-Net+
    WIP: Server+
  6. grim

    grim Gigabyte Poster

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    wont the router establish the connection, i thought the DSU/CSU just filtered the signal like a filter on a DSL conenction ?

    Do we need DSU/CSUs on E1 connections ?

    GRim
     
    Certifications: Bsc, 70-270, 70-290, 70-291, 70-293, 70-294, 70-298, 70-299, 70-620, 70-649, 70-680
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  7. hbroomhall

    hbroomhall Petabyte Poster Gold Member

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    No - a pure router just routes on Ethernet connections. It doesn't know about WAN type signals. (Over simplification here... <grin> )

    The problem is that we often talk about our 'router' at home, not always realizing that it isn't a router only - it is a combination device of modem, router and switch (plus other things as well).
    As I said before - it is effectively a modem, not a filter.
    You need *something* to convert the WAN signalling to something usable on a LAN. The term DSU/CSU seems to be restricted to North America (unless someone can show me otherwise). The equivalent functionality is supplied in the UK by a NTU.

    Harry.
     
    Certifications: ECDL A+ Network+ i-Net+
    WIP: Server+

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