1. Introduction to PPP

2. Using dial-up modems for packet-oriented- networking (i.e connecting to the internet) requires a data-link layer protocol widely-spread protocols: SLIP PPP HDLC History

3. SLIP - Serial Line Internet Protocol Defined in the early 80`s Purpose extending TCP/IP networking with dial-up serial connection Users unix users at the beginning and PC users later Advantages Very simple protocol Easy implementation

4. SLIP - Serial Line Internet Protocol Disadvantages Does not support error detction and correction Supports only IP (and not IPX/SPX etc`) Requires advance knowledge of the peer`s IP address Is not approved internet standard Does not provide any form of authentication

5. PPP – design principles Support multiple network protocols Link configuration Error detection Establishing network addresses Authentication Extensibility

6. PPP – a layered protocol PPP relies on another DLP – HDLC – to perform some basic operations After the initial handshake, PPP executes its own handshake PPP itself consists of two protocols: LCP – Link Control Protocol NCP – Network Control Protocol

7. 7 Point-to-Point Protocol Point-to-Point Protocol (PPP) is a byte-oriented protocol developed in 1990s as a replacement for SLIP. The packet begins and ends with a flag “01111110”. Therefore, it suffers the transparency problem. CRC-16 for error control Supports network layer protocols other than just Internet protocol. Message length is up to 1500 bytes.

8. PPP – frame format Protocol type of information in data/padding field (I.e: IP, IPCP, LCP, CHAP etc`) Data/Padding data for the upper layer protocols or PPP control packets dataprotocolflagaddrcontrol padding check PPP frame

9. LCP Purposes Link establishment Link maintenance Link termination Optional operations Link quality determination Authentication

10. LCP – packets Purpose There are 3 classes of LCP packets: Link configuration configure-request, configure-ack, configure-nak & configure-reject Link termination terminate-request & terminate-ack Link monitoring code-reject, protocol-reject, echo-request, echo-reply & discard-request

11. NCP Purpose Configuring the network layer protocol. There exists a separate NCP for each network layer protocol Negotiation process Same message formats, code numbers and state machines as LCP

12. PPP – unsupported options Flow control Any PPP frame sent that overflows the receiver's buffer are lost Error correction PPP includes only Frame Check Sequence (CRC) Re-sequencing PPP assumes all frames, sent and received, retain their original intended order

13. Tunneling - definition The process of running one network protocol on top of another. Common use: VPN (Virtual Private Network) Tunneling method Extending the link between the HDLC driver and the rest of PPP over a separate network PPP tunneling protocols L2TP, L2F, PPTP & ethernet (PPPoE) Tunneling & PPP

15. HDLC Definition High-level Data Link Control, Bit-oriented link protocol published by ISO foundation for other protocols (examples ) Operations 1 st stage – frame formation 2 nd stage – medium-dependant frame transmission

16. 3 variable-length fields Address – intended for multidrop links Control – specifies the type of message transmitted Information – content transferred by the top level application 1 fixed-length field Check HDLC – frame format addresscontrolinformationcheck HDLC frame

17. Internet layered architechture Application Transport Network Data Link Physical Media, clocking and synchronization Data link operations (???) Forwarding and route discovery Port and traffic management End-user application

18. PPP – design principles Support multiple network protocols Link configuration Error detection Establishing network addresses Authentication Extansibility Not limited to the internet and other TCP/IP networks, I.e: IPX/SPX and IPv6 Includes nagotiation mechanisms for establishing communication parameters betweens two PPP peers Detects datagrams corruption upon reception and discards such corrupted data Sets network addresses necessary for the datagrams routing Supports authentication between peers before useful communication begins Yet, maintains backward compatibility

19. HDLC(High-level Data Link Protocal) 1.It is a bit-oriented synchronous protocol. 2.HDLC is Data Link Layer Protocl and it is a Communication Protocol. 3.HDLC is Cisco proprietary protocol and Developed by ISO and it is developed out of IBM'S SDLC(Synchronous Data Link Protocol) 4.HDLC is superset of SDLC. 5.It supports only Synchronous communication. 6.It has 3 transfer modes of Normal Response mode (NRM),Asynchronous Response Mode(ARM),Asynchronous Balanced Mode(ABM). PPP(Point To Point Protocol) 1.It is a byte-oriented synchronous protocol. 2.It is used for direct Communication between 2 nodes, It has no transfer mode like HDLC. 3.3. It is not a Cisco Proprietary. 4.PPP is type of HLDC. 5.It supports encryption, authentication and Comparison. 6.Authentication Support by PAP (password authentication protocol) and also by CHAP(Challange Handshake Protocol).

20. THANK YOU.