Ce1/Pri Interface Overview - Huawei AR1200 series Configuration Manual

Huawei AR1200 Series Enterprise Routers
Configuration Guide - Interface Management

6.1 CE1/PRI Interface Overview

This section describes the principles of CE1/PRI interfaces.
Introduction to E1 and T1
The Pulse Code Modulation (PCM) technology promotes the application of the Time Division
Multiplexing (TDM) technology in the digital communication system. Currently, two TDM
systems are available in the digital communication system:
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Unchannelized, Fractional Channelized, and Channelized
An E1 physical interface can work in the following modes:
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Introduction to CE1/PRI Interface
A CE1/PRI interface can work in unchannelized or channelized mode.
A CE1/PRI interface has the following characteristics:
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Issue 01 (2012-04-20)
E1: a 30/32 channel system used in China and Europe. E1 has 32 timeslots, and each
timeslot has a rate of 64 kbit/s. Therefore, E1 works at a rate of 2.048 Mbit/s.
T1: a 24 channel system used in North America. T1 has 24 timeslots, all of which can be
used to transmit data. Therefore, T1 works at a rate of 1.544 Mbit/s.
Unchannelized mode: An E1 physical interface functions as a synchronous serial interface
without timeslot bundle.
Fractional channelized mode: An interface has only one channel, which contains one or
more timeslots.
Channelized mode: The interface can have multiple channels. Each channel can be formed
by bundling one or more timeslots.
In E1 mode, a CE1/PRI interface works at a rate of 2.048 Mbit/s without timeslot bundle.
Similar to a synchronous serial interface, a CE1/PRI interface supports link layer protocols
such as the Point-to-Point Protocol (PPP) and Frame Relay (FR) and network protocols
such as the Internet Protocol (IP) and Internetwork Packet Exchange (IPX).
In CE1/PRI mode, the 2 Mbit/s transmission line of a CE1/PRI interface is divided into 32
timeslots at a rate of 64 kbit/s. The 32 timeslots are numbered 0 to 31, and timeslot 0
transmits synchronization signals.
A CE1/PRI interface working in CE1/PRI mode functions as either a CE1 interface or a
PRI interface.
– When the CE1/PRI interface functions as a CE1 interface, timeslots except timeslot 0
can be randomly bundled to form multiple channel sets. Each channel set functions as
a serial interface. A serial interface has the same logical features as a synchronous serial
interface, such as supporting link layer protocols (such as PPP, HDLC, and FR) and
network protocols (such as IP).
– When the CE1/PRI interface functions as a PRI interface, timeslot 16 functions as the
D channel to transmit signals. Therefore, only one group of timeslots except timeslots
0 and 16 can be randomly selected to function as a B channel, and then the B channel
is bundled with timeslot 16 to form a PRI set. The PRI set functions as an ISDN PRI
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