chapter 3 part 2

Question 1

what is the default encapsulation protocol for serial/ leased line links?

Answer 1

HDLC

Question 2

when using non cisco devices for a Serial link then what type of encapsulation should be used?

Answer 2

PPP

Question 3

what layer of the OSI does the encapsulation PPP or HDLC on a serial link use?

Answer 3

layer 2: Data link layer

Question 4

what features does PPP offer that HDLC does not offer?

Answer 4

Authentication (PAP and CHAP) , link quality feature: if too many errors then the link is taken down.

Question 5

what do LCP and NCP do in PPP and on what OSI layer are these?***important to know diff between what LCP and NCP does.

Answer 5

network or layer 3 OSI. NCP: Network Control Protocol- does higher level protocol configs. LCP- Link Control Protocols: authenticates the connection and terminates connection over PPP. also helps agree on types of compression and error detection.

Question 6

what kind of LCP options are there for PPP?

Answer 6

compression, authentication, error detection., mutilink and call back.

Question 7

what type of LCP (link control protcol) authentication is there?

Answer 7

PAP: Password Authentication Protcol and CHAP: Challenge Handshake Authentication Protocol

Question 8

how does PAP work and what is it?

Answer 8

Password Authenticate Protocol: no encryption. username and password sent as plain text from router to receiver device, keeps sending until sending router gets an AKN or the connection is terminated.

Question 9

what is CHAP how does it work?

Answer 9

Challenge Handshake Authentication Protocol: 3 way handshake. challenge question sent, respond with username and pword, if pword is correct then ACK sent back and connection made. periodic challenge questions to make sure the sender is legit.