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CLI-based Configuration Guide - Interface Management

AR100, AR120, AR160, AR1200, AR2200, AR3200, and AR3600 V300R003

This document provides the basic concepts, configuration procedures, and configuration examples of the interfaces supported by the device.
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Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
Overview of CE1/PRI Interfaces

Overview of CE1/PRI Interfaces

A CE1/PRI interface is a physical interface in the E1 system, which can transmit voice, data, and video service packets.

The Pulse Code Modulation (PCM) technology was developed in 1960s and allows the Time Division Multiplexing (TDM) technology to be widely applied in the digital communication system. There are two TDM systems in the digital communication system: E1 system and T1 system. The E1 system is recommended by ITU-T and used in Europe and China. The T1 system is recommended by ANSI and used in North America and Japan. (Actually, Japan uses the J1 system, which is similar to the T1 system.)

A CE1/PRI interface is a physical interface in the E1 system. It can work in E1 mode (unchannelized mode) or CE1/PRI mode (channelized mode).

  • In E1 mode, a CE1/PRI interface works at a rate of 2 Mbit/s without timeslot division. 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 the Internet Protocol (IP).
  • The CE1/PRI interface working in CE1/PRI mode functions as either a CE1 interface or a PRI interface. In CE1/PRI mode, the 2 Mbit/s transmission line of the 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.

    • CE1 interface: All the timeslots except timeslot 0 can be bundled into several channel sets. Each channel set maps a channel. Each channel set functions as an interface, which has the same logical features as a synchronous serial interface and supports link layer protocols (PPP, HDLC, and FR) and IP.
    • 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 interface and supports link layer protocols (PPP and FR) and IP.

This section provides only the physical attribute configuration of ISDN PRI interfaces. For details about ISDN service configuration, see ISDN Configuration in the Configuration Guide - WAN.

Clock Mode

To exchange data correctly, communicating parties must have their clocks synchronized.

A CE1/PRI interface works in either of the two clock modes:
  • Master clock mode (local clock mode): In this clock mode, a T1-F interface uses the local clock generated by the chip as the reference clock.
  • Slave clock mode (line clock mode): In this clock mode, a T1-F interface uses the line clock as the reference clock.

Generally, the interface at one end of a link works in master clock mode, and the interface at the other end works in slave clock mode.

Frame Format

A CE1/PRI interface supports two frame formats:
  • CRC4 format: A CRC4 multiframe is formed by the first bit in each frame transmitted over timeslot 0. This format contains 16 consecutive pulse code modulation (PCM) frames.
  • Non-CRC4 format (basic frame format): This format is also called the dual-frame format or odd-even frame format. An even frame in timeslot 0 transmits frame alignment signal 0011011. An odd frame in timeslot 0 has a fixed value 1 in the second bit, which distinguishes it from an even frame with value 0 in the second bit.

Line Idle Code

The line idle code is the code sent over a timeslot that is not bundled to form a channel.

The router supports two line idle codes: 0x7e and 0xff.

Interframe Filling Tag

The interframe filling tag is the code sent when the timeslot bundled to form a logical channel does not send any service data.

The router supports two interframe filling tags: 0x7e and 0xff. On the router, you can set the minimum number of interframe filling tags.

AIS Detection

Alarm indication signal (AIS) alarms are also called upstream alarms, indicating that the peer device or the receive link of the local device is faulty.

If the number of 0s in 512 consecutive bits (two consecutive frames) of a received signal is smaller than 3, an AIS alarm is generated. If the number of 0s in 512 consecutive bits of a received signal is larger than or equal to 3, an AIS alarm is cleared.

RAI Detection

A remote alarm indication (RAI) alarm is sent to an upstream device after the router detects loss of frame (LOF) caused by clock asynchronization or loss of signal (LOS).

Updated: 2019-03-06

Document ID: EDOC1100069331

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