In this presentation I tried to cover three topics Intro to PPP Frame Structure Encapsulation and Establishment of PPP

1. Syed Ali Jafar Zaidi

2. • It is a protocol of data link layer.
• PPP is used to established a direct
connection between two nodes.
• It provides connection authentication
transcription and compression
• PPP is use over many types of physical
networks including serial cable and phone
cable.

4.  PPP goes through four distinct phases to
provide communications over point-to-
point links
1. Link establishment & configuration negotiation
2. Link quality determination
3. Network-layer protocol configuration negotiation
4. Link termination

5.  Flag - Set to 0x7E (bit sequence 011111110) to
signify the start and end of a PPP frame. In
successive PPP frames only a single Flag
character is used.
 Address - In HDLC environments, the Address
field is used to address the frame to the
destination node. On a point-to-point link, the
destination node does not need to be addressed.
Therefore, for PPP, the Address field is set to
0xFF, the broadcast address. If both PPP peers
agree to perform address and control field
compression during LCP negotiation, the

6.  Address field is not included.
 Control - In HDLC environments, the Control field is
used for data-link layer sequencing and
acknowledgments. PPP does not provided link-to-link
reliable data transfer. Therefore, for all PPP frames, the
Control field is set to 0x03 to indicate an unnumbered
information (UI) frame. If both PPP peers agree to
perform address and control field compression during
LCP negotiation, the Control field is not included.
 Protocol ID - The 2-byte Protocol ID field identifies the
protocol of the PPP payload. If both PPP peers agree to
perform protocol field compression during LCP
negotiation, the Protocol ID field is one byte for Protocol
IDs in the range 0x00-00 to 0x00-FF.

7. Frame Check Sequence (FCS) - A 16-bit
checksum that is used to check for bit level
errors in the PPP frame. If the receiver's
calculation of the FCS does not match the
FCS in the PPP frame, the PPP frame is
silently discarded.