Basic Rate Interface

<h2 id="physical-interfaces">Physical interfaces</h2>
<p>The BRI is split in two sections:
a) in-house cabling (S/T reference point or S-bus) from the ISDN terminal up to the <a href="/facts/Network_termination_1/1bRVj65p">network termination 1</a> (NT1) and
b) transmission from the NT1 to the central office (U reference point).
</p>
<ul><li>The in-house part is defined in <a href="/facts/I.430/NuUzHYty">I.430</a> produced by the <a href="/facts/International_Telecommunication_Union/Yn8UKKkw">International Telecommunication Union</a> (ITU). The S/T-interface (<a href="/facts/S_interface/YWWkuBpN">S0</a>) uses four wires; one pair for the <a href="/facts/Uplink/wCxVKCKo">uplink</a> and another pair for the <a href="/facts/Downlink/wCxVKCKo">downlink</a>. It offers a full-duplex mode of operation. The I.430 protocol defines 48-bit <a href="/facts/Data_packet/xCYf8SJu">packets</a> comprising 16 <a href="/facts/Bit/S972NSaD">bits</a> from the B1 channel, 16 bits from B2 channel, 4 bits from the D channel, and 12 bits used for <a href="/facts/Synchronization/L39sYwbr">synchronization</a> purposes. These packets are sent at a rate of 4 <a href="/facts/Kilohertz/6Wshj5qm">kHz</a>, resulting in a gross <a href="/facts/Bit_rate/ppUNMmVd">bit rate</a> of 192 kbit/s and – giving the data rates listed above – a maximum possible throughput of 144kbit/s. The S0 offers point-to-point or point-to-multipoint operation; Max length: 900 metres (3,000 ft) (point-to-point), 300 metres (980 ft) (point-to-multipoint).</li>
<li>The <a href="/facts/U_interface/xdl8HjNT">Up Interface</a> uses two wires. The gross bit rate is 160 kbit/s; 144 kbit/s throughput, 12 kbit/s sync and 4 kbit/s maintenance. The signals on the U reference point are encoded by two modulation techniques: 2B1Q in North America, Italy and Switzerland, and 4B3T elsewhere. Depending on the applicable cable length, two varieties are implemented, UpN and <a href="/facts/Up0-interface/RdPmH6bf">Up0</a>. The <a href="/facts/UK0-Interface/xdl8HjNT">Uk0</a> interface uses one wire pair with <a href="/facts/Echo_cancellation/Q26toK4x">echo cancellation</a> for the long <a href="/facts/Last_mile_(telecommunications)/8TkkKm8e">last mile</a> cable between the <a href="/facts/Telephone_exchange/PaRpGm8I">telephone exchange</a> and the <a href="/facts/Network_termination_1/1bRVj65p">network terminator</a>. The maximum length of this BRI section is between 4 and 8 kilometres (2.5 and 5.0 mi).</li></ul>

<h2 id="external-links">External links</h2>
<ul><li><a href="https://web.archive.org/web/20120825163144/http://www.birds-eye.net/definition/b/bri-basic_rate_interface.shtml">"BRI defined on birds-eye.net"</a>. Archived from <a href="http://www.birds-eye.net/definition/b/bri-basic_rate_interface.shtml">the original</a> on 2012-08-25. Retrieved 2012-08-25.</li></ul>

<h2 id="references">References</h2>

<ol>
<li id="fn:1"><p>This article is based on material taken from Basic+Rate+Interface at the Free On-line Dictionary of Computing  prior to 1 November 2008 and incorporated under the "relicensing" terms of the GFDL, version 1.3 or later. <a href="https://foldoc.org/Basic+Rate+Interface" target="_blank">https://foldoc.org/Basic+Rate+Interface</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li>
</ol>

Basic Rate Interface open-in-new

Basic Rate Interface