When the PDU moves up or down in the OSI layer, the process of adding information to the PDU header is named encapsulation, correct ? So why it has been said that "encapsulation" occurs in the data link layer ? ___________________________________ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]