HDLC and Point to point protocol

All about HDLC and Point to point protocol.

1. HDLC & PPP Presented By: KINZA RAZZAQ

2. HDLC HDLC(High-Level Data Link Control) is a group of protocols or rules for transmitting data between network points(nodes).

3. Working In HDLC, the date is organized into a unit(frame) and sent across a network to a destination that verifies it’s successful arrival. The HDLC protocol also manages the flow or pacing(stepping) at which the data is being sent

4. Features HDLC is one of the most commonly used protocol and support full duplex approach. Broadly HDLC features are as follows: Reliable protocol selective repeat or go-back-N Full-duplex communication receive and transmit at the same time Bit-oriented protocol use bits to stuff flags occurring in data. Flow control adjust window size based on receiver capability Uses physical layer clocking and synchronization to send and receive frames

5. Stations

6. Balanced & Unbalanced Mode . Primary Secondary Secondary Commands Responses Combined Combined commands/Responses Unbalanced Mode Balanced mode

7. Frames

8. Point-to-point Protocol In computer networking, Point-to-Point Protocol  (PPP) is a data link  (layer 2)  protocol used to establish a direct connection between two nodes.

9. Connection It connects two routers directly without any host or any other networking device in between. It can provide connection authentication, transmission encryption.

10. Origin PPP was designed somewhat after the original HDLC(High-Level Data Link Control) specifications. The designers of PPP included many additional features that had been seen only in proprietary(branded) data-link protocols up to that time. PPP was designed to work with numerous network layer protocols, including Internet Protocol (IP), Novell's Internetwork Packet Exchange (IPX), etc. PPP is specified in RFC 1661.

11. Usage PPP is used over many types of physical networks including serial cable, phone line, trunk line, cellular telephone, specialized radio links, and fiber optic links. PPP is also used over Internet access connections. Internet service providers (ISPs) have used PPP for customer dial-up access to the Internet, since IP packets cannot be transmitted over a modem line on their own, without some data link protocol.

12. Usage PPP is commonly used as a data link layer protocol for connection over synchronous and asynchronous circuits, where it has largely superseded (outdated) the older Serial Line Internet Protocol (SLIP) and telephone company mandated standards (such as Link Access Protocol, Balanced (LAPB). The only requirement for PPP is that the circuit provided be duplex. Like SLIP, this is a full Internet connection over telephone lines via modem. It is more reliable than SLIP because it double checks to make sure that Internet packets arrive intact(complete). It resends any damaged packets.

13. Derivatives

14. Components PPP is a layered protocol that has three components: An encapsulation component that is used to transmit datagrams   (unit of transfer) over the specified physical layer. A Link Control Protocol (LCP) to establish, configure, and test the link as well as negotiate capabilities. One or more Network Control Protocols (NCP) used to negotiate optional configuration parameters and facilities for the network layer. There is one NCP for each higher-layer protocol supported by PPP.

15. Looped Link Detection PPP detects looped links using a feature involving magic numbers. When the node sends PPP LCP messages, these messages may include a magic number. If a line is looped, the node receives an LCP message with its own magic number, instead of getting a message with the peer's magic number.

16. Configuration Options Authentication  - Peer routers exchange authentication messages. Two authentication choices are Password Authentication Protocol (PAP) and Challenge Handshake Authentication Protocol (CHAP). Compression  - Increases the effective throughput on PPP connections by reducing the amount of data in the frame that must travel across the link. The protocol decompresses the frame at its destination. Error detection  - Identifies fault conditions. The Quality and Magic Number options help ensure a reliable, loop-free data link. The Magic Number field helps in detecting links that are in a looped-back condition. Until the Magic-Number Configuration Option has been successfully negotiated, the Magic-Number must be transmitted as zero. Magic numbers are generated randomly at each end of the connection.

17. Line Activation & Phase