CPET/ECET 355
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Transcript of CPET/ECET 355
10/27/200411. Data Link Control and Protocols - Lin1
CPET/ECET 355CPET/ECET 35512. Point-to-Point Access:
PPP
Data Communications and NetworkingFall 2004
Professor Paul I-Hai LinElectrical and Computer Engineering TechnologyIndiana University-Purdue University Fort Wayne
www.ecet.ipfw.edu/~lin
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Point-to-Point Access: PPPPoint-to-Point Access: PPP
Data Link Protocol for– Dial-up modems– DSL modems– Cable modems
PPP Defines– Frame format– Negotiate and establish exchange of data– Encapsulation of network layer data– Authentication
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PPP – Frame FormatPPP – Frame Format
Address Field Control Field Protocol Field Data Field Frame Check Sequence (FCS)
From p. 296, Figure 12.1 of Data Communications and Networking, Forouzan, McGrawHill
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PPP – Transition StatesPPP – Transition States Idle, Establishing, Authenticating,
Networking, Terminating
From p. 296, Figure 12.2 of Data Communications and Networking, Forouzan, McGrawHill
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PPP – StackPPP – Stack Three Protocols
– Link Control protocol– Authentication protocol, and – Network Control protocol
From p. 297, Figure 12.3 of Data Communications and Networking, Forouzan, McGrawHill
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PPP – Link Control ProtocolPPP – Link Control Protocol LCP Responsibilities
– Establishing, Maintaining, Configuring, and Terminating Links
– Payload: Code, ID, Length, Information Fields
From p. 298, Figure 12.4 of Data Communications and Networking, Forouzan, McGrawHill
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PPP – LCP PacketsPPP – LCP Packets
From p. 298, Table 12.1 of Data Communications and Networking, Forouzan, McGrawHill
Code Packet Type Description
0116 Configure-request Contains the list of proposed options and their values
0216 Configure-ack Accepts all options proposed
0316 Configure-nak Announces that some options are not acceptable
0416 Configure-reject Announces that some options are not recognized
0516Terminate-request Requests to shut down the line
0616 Terminate-ack Accepts the shut down request
0716 Code-reject Announces an unknown code
0816 Protocol-reject Announces an unknown protocol
0916 Echo-requestA type of hello message to check if the other end is alive
0A16 Echo-reply The response to the echo-request message
0B16 Discard-request A request to discard the packet
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PPP – LCP PacketsPPP – LCP Packets
Configuration Packets– Configuration-request– Configuration-ack– Configuration-nak– Configuration-reject
Link Termination Packets– Termination-request– Termination-ack
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PPP – LCP PacketsPPP – LCP Packets
Link Monitoring and Debugging Packets– Code-reject– Protocol-reject– Echo-request– Echo-reply– Discard-request
Options (in the info field)
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LCP Packet OptionLCP Packet Option
From p. 298, Figure 12.4 of Data Communications and Networking, Forouzan, McGrawHill
Option Default
Maximum receive unit 1500
Authentication protocol None
Protocol field compression Off
Address and control field compression Off
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Authentication ProtocolsAuthentication Protocols Password Authentication Protocols
(PAP)– User sends ID (user name), and Password– System checks the validity: accept, or reject
Challenge Handshake Authentication Protocols (CHAP) – System send a challenge packet– The user applies a predefined function, and
reply the challenge packet– The system does the same to see if the
same result can be obtained: accept or reject
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PAP (Password Authentication)PAP (Password Authentication)
From p. 300, Figure 12.5 of Data Communications and Networking, Forouzan, McGrawHill
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PAP PacketsPAP Packets
From p. 301, Figure 12.6 of Data Communications and Networking, Forouzan, McGrawHill
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CHAP CHAP
From p. 302, Figure 12.7 of Data Communications and Networking, Forouzan, McGrawHill
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CHAP PacketsCHAP Packets
From p. 302, Figure 12.8 of Data Communications and Networking, Forouzan, McGrawHill
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Network Control Protocol (NCP)Network Control Protocol (NCP)
From p. 303, Figure 12.9 of Data Communications and Networking, Forouzan, McGrawHill
IPCP: Internetwork Protocol Control Protocol
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Code Values for IPCP PacketsCode Values for IPCP Packets
From p. 303, Table 12.3 of Data Communications and Networking, Forouzan, McGrawHill
Code IPCP Packet
01 Configure-request
02 Configure-ack
03 Configure-nak
04 Configure-reject
05 Terminate-request
06 Terminate-ack
07 Code-reject
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PPP Connection ExamplePPP Connection Example
From p. 303, Figure 12.9 of Data Communications and Networking, Forouzan, McGrawHill
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SummarySummary
Questions?