APNIC Training

eIRM08: 4-Byte ASN

eIRM08: 4-Byte ASN

DeliveryeLearning (this course is conducted online)
Duration1 hour
Level of StudyIntermediate


An Autonomous System Number (ASN) is a global unique number that identifies an autonomous system and is necessary for exchanging exterior routing information. AS numbers are normally represented using a 2-byte number field. Recently a 4-byte AS number pool has been introduced to address the exhaustion of the 2-byte ASN.

This eLearning course introduces participants to the 4-byte AS number representation, operational implications and interoperability with the old numbering scheme.

Target Audience:

This course is designed for network engineers, systems administrators, and anyone who is involved in managing Internet resources.


Sound understanding of Internet networking and Routing fundamentals.

It is recommended that the participants attend eIRM05 course prior to attending this course.

Course Outline:

  • AS Numbers
  • 4-byte AS Number Representation
  • AS Path Attribute
  • 4-byte AS Transition (with Example)

Other requirements:

  • Updated web browser with Adobe Flash Player 11 or above
  • Broadband connection running at a minimum of 256kbps or better
  • Headset (to reduce noise)

Maximum number of attendees:

50 participants per session


  • Free

All eLearning courses are free of charge for participants, with priority given to APNIC Members.

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Download slides for this course (861.4 KB).