CSU/DSU

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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

 

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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.

 

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?

 

No ones actually added to my thread

GRim

 

Partially true!

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.

 

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

 

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.