High-level Data Link Control (HDLC) is a common link layer technology in use today. The two main functions of HDLC are link management and data transfer. As part of the data transfer, HDLC provides error detection and flow control.
Although HDLC is the default encapsulation on a Cisco serial interface, it can be manually configured using the following interface command:
Router(config-int)# encapsulation hdlc
The current encapsulation on a serial interface can be viewed with the show interface command:
Router# sho int s0/0/0Serial0/0/0 is administratively down, line protocol is down Hardware is GT96K Serial MTU 1500 bytes, BW 1544 Kbit/sec, DLY 20000 usec, reliability ...