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E3 Interfaces Overview


E3 is a high-speed WAN digital communication technique designed to operate over copper facilities at a rate of 34.368 Mbps. Widely used outside North America, it is the time-division multiplexing scheme used to carry 16 E1 circuits. The following standards apply to E3 interfaces:

  • ITU-T Recommendation G.703, Physical/electrical characteristics of hierarchical digital interfaces, describes data rates and multiplexing schemes for the E Series.

  • ITU-T Recommendation G.751, General Aspects of Digital Transmission Systems: Terminal Equipment, describes framing methods.

  • ITU-T Recommendation G.775, Loss of Signal (LOS) and Alarm Indication Signal (AIS) Defect Detection and Clearance Criteria, describes alarm reporting methods.

The Junos OS supports the E3 Physical Interface Card (PIC) and the E3 Intelligent Queuing (IQ and IQE) PICs. The E3 IQ and E3 IQE PICs supports transmission scheduling on logical interfaces. For more information, see the Class of Service User Guide (Routers and EX9200 Switches).


In unframed mode, the E3 IQ and E3 IQE PICs do not detect yellow or loss-of-frame alarms.

Related Documentation