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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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Overview of E1-F Interfaces

Overview of E1-F Interfaces

An E1-F interface is a simplified CE1/PRI interface and can transmit voice, data, and video service packets.

If E1 access does not require multiple channels sets or ISDN PRI, using a CE1/PRI interface is a waste of resources. In this scenario, you can use an E1-F interface to provide the E1 access service. Compared with a CE1/PRI interface, an E1-F interface provides E1 access at a low cost.

An E1-F interface works in either of the following modes:
  • In unframed mode, an E1-F interface works at a rate of 2048 kbit/s without timeslot bundle.
  • In framed mode, an E1-F interface is divided into 32 timeslots, which are numbered 0 to 31. Timeslot 0 transmits frame alignment signals. Any random group of timeslots 1 to 31 can be bundled into a channel. The rate of an E1-F interface is n x 64 kbit/s, in which n is the number of timeslots bundled into a channel.

In either unframed mode or framed mode, an E1-F interface is similar to a synchronous serial interface and supports link layer protocols such as the Point-to-Point Protocol (PPP), High-Level Data Link Control (HDLC), and Frame Relay (FR) and network protocols such as IP.

An E1-F interface differs from a CE1/PRI interface in the following aspects:

  • When working in framed mode, an E1-F interface allows timeslots to be bundled into only one channel, whereas a CE1/PRI interface allows timeslots to be randomly bundled into multiple channels.
  • An E1-F interface does not support the PRI mode.

Clock Mode

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

An E1-F 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

An E1-F 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).

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Updated: 2019-03-06

Document ID: EDOC1100069331

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