What is the difference between HDLC and GFP encapsulation?
HDLC encapsulation has been used in legacy systems for several decades. However, HDLC suffers a problem when the “flag sequence” used to denote the start and end of a frame occurs natively in the data being transported. HDLC must substitute the offending sequence with a longer nonoffending sequence. In the worst cases, this can choke the available bandwidth down to 50% of the expected value. GFP avoids this problem by using a length-indicating header with error correction. Because of the predictable overhead, GFP is generally the preferred encapsulation method for new systems. The DS33X162 family of products supports both HDLC and GFP.
