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New Member

T1 over HDSL question, Please Help

Do most new T1 installations run over HDSL today and do most T1 lines already installed run over HDSL?

I was told by my service provider that my T1 runs over HDSL and that I only use 768 for transmit and 768 for receive which equals a T1 line. They also told me that all new T1 intallations run over HDSL. I thought I should be getting 1.5 Mbps transmit and 1.5 Mbps receive simultaneously.

Thanks for any responses.

New Member

Re: T1 over HDSL question, Please Help

Yes most new T1's are over the HDSL protocol. At least in our area. BUT a T1 is still 1.544mbps in both directions. minus overhead it should be 1.536mbps bidirectional.

If your provider is only providing 768kbps then ether they are shorting you or they do not know what they are talking about. Try to talk with a higher level tech and see if the answer is differnet.


New Member

Re: T1 over HDSL question, Please Help

When you say "but a T1 is 1.544mbps in both directions", do you mean I should receive 1.544 Mbps transmit and receive at the same time?


Re: T1 over HDSL question, Please Help

Yes, a full T1 is 1.544 (really 1.536M) in both directions, at the same time (full duplex).

What he may have been saying is that you have frame-relay (Fractional T1/DS1 is delivered using T1 signaling, probably over an HDSL line ... the NUI/SmartJack does the conversion to "T1/DS1")

With frame-relay, it's common to have fractional bandwidth (like 768K). IN addition to that, 768K sounds like your "Access Rate," .... you may actually be provisioned for less as a Comitted Information Rate" (CIR) ... like maybe 384K, with burst allowed up to the Access Rate (768K).

T1/DS1 is the low-level / Layer One protocol, over that you can have a variety of Layer Two protocols (one at a time) ... like Frame-Relay, HDLC, or PPP.