Configuring and Verifying PPP (Point to Point Protocol) on CISCO Routers

Enable PPP to an interface
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On R1
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R1(config)#interface se0/0/0
R1(config-if)#encapsulation ppp


On R2
=====
R2config)#interface se0/0/0
R2config-if)#encapsulation ppp

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Enable Authentication
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on Router R1
===============
R1(config)#username R2 password cisco
R1(config)#interface se0/0/0
R1(config-if)#ppp authentication chap

on Router R2
=================
R2(config)#username R1 password cisco
R2(config)#int se0/0/0
R2(config-if)#ppp authentication chap


If you wnat to verify the PPP authentication
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R1#debug ppp authentication