HDLC vs PPP | Difference between HDLC and PPP

High-level data link control (HDLC) and Point-to-Point(PPP) are two different data link layer protocols used in computer networks. the primary difference between HDLC and PPP is that HDLC is a bit-oriented protocol whereas PPP is a byte-oriented protocol.

What is HDLC?

HDLC stands for high-level data link protocol, It is an asynchronous data link layer protocol with bit-oriented code transparency. The International Organization for Standardization created it. Furthermore, it accommodates both connection-oriented and connectionless services.

What is PPP?

PPP stands for point-to-point protocol, it is another WAN encapsulation protocol that is based on HDLC, but it is an improved version of HDLC. When compared to HDLC, PPP has a plethora of additional features.

Difference between HDLC and PPP | HDLC vs PPP:

  • HDLC is a bit-oriented protocol, whereas PPP is both byte-oriented and bit-oriented due to its ability to be transmitted over dial-up modem lines as well as true bit-oriented HDLC.
  • HDLC does not support link authentication, whereas PPP does.
  • HDLC operates at layer 2 called as data link layer, while the PPP is operating at layer 2, and layer three is called the network layer.
  • PPP can dynamically assign and free up IP addresses based on their use. In HDLC however, this is not the case.
  • In HDLC only synchronous media can be used, PPP can work with both synchronous and asynchronous media.
  • HDLC interoperability between non-cisco devices is not possible. This limitation of HDLC, however, is removed from the PPP protocol.
  • HDLC lacks an error detection method, whereas PPP employs FCS to detect errors while transmitting data.
  • HDLC protocols have two types via ISO, HDLC, and CISCO HDLC, while the PPP uses HDLC a format as defined by ISO.
  • HDLC is used to encapsulate data without the assistance of other encapsulation protocols, whereas PPP can encapsulate data without the assistance of other encapsulation protocols such as HDLC and SDLC.
  • HDLC fails to check for the quality of the link established, while the PPP uses link control protocol to check for the quality of the established link.
  • HDLC does not support authentication. It fails to provide authentication between two nodes. While the PPP supports authentication using a protocol such as PAP and CHAP.

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