ADTRAN 1200060L1, Руководство пользователя

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Chapter 1. Introduction
1-2 TSU User Manual 61200060L1-1
performance of their service offering. Since the introduction
of ESF, equipment that is installed in private networks can
also provide the same performance information to the user.
Fractional T1
Fractional T1 lets the buyer purchase less than a full T1
circuit between two points. Most carriers offer fractional T1
in increments of 56 or 64 kbps. Connection is made to the
same network elements. The network allows multiple users
to share the same interoffice T1 bandwidth.
Fractional T1 remains almost exclusively an Inter-Exchange
Carrier (IXC) service. Local Exchange Carriers (LECs)
typically do not offer FT1, so the user's proximity to the IXC's
point of presence (POP) is key in the savings that fractional
T1 offers.
Fractional T1 local access is available in two forms, 56kbps or
a full T1 line. In 56 kbps the required number of DDS lines is
extended from the IXC POP and the bandwidth is combined
at the office on an outbound T1 circuit. The user pays for the
individual 56K lines and the amount of the interoffice T1
utilized. In T1 access, the user pays for a full T1 to the IXC
POP and then only for the bandwidth utilized.