Datasheet

Lab – Configuring Basic PPP with Authentication

.Jun 20 02:30:36.596: Se0/0/0 PPP: Session handle[34000005] Session id[5]

.Jun 20 02:30:36.596: Se0/0/0 LCP: Event[OPEN] State[Initial to Starting]

What happens when one end of the serial link is encapsulated with PPP and the other end of the link is

encapsulated with HDLC?

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The link goes down, and the OSPF adjacency is broken. PPP keeps trying to establish a connection with

the opposite end of the link as indicated by the message “Phase is ESTABLISHING”. However, because

it keeps receiving a non-NCP packet, LCP fails to negotiate and the link stays down.

f. Issue the encapsulation ppp command on the S0/0/0 interface for the Branch1 router to correct

mismatched encapsulation.

Branch1(config)# interface s0/0/0

Branch1(config-if)# encapsulation ppp

g. Observe the debug PPP messages from the Branch1 router as the Branch1 and Central routers establish

a connection.

Branch1(config-if)#

Jun 20 03:01:57.399: %OSPF-5-ADJCHG: Process 1, Nbr 209.165.200.225 on Serial0/0/0

from FULL to DOWN, Neighbor Down: Interface down or detached

Jun 20 03:01:59.399: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/0,

changed state to down

Jun 20 03:01:59.399: Se0/0/0 PPP: Sending cstate UP notification

Jun 20 03:01:59.399: Se0/0/0 PPP: Processing CstateUp message

Jun 20 03:01:59.399: PPP: Alloc Context [30F8D4F0]

Jun 20 03:01:59.399: ppp9 PPP: Phase is ESTABLISHING

Jun 20 03:01:59.399: Se0/0/0 PPP: Using default call direction

Jun 20 03:01:59.399: Se0/0/0 PPP: Treating connection as a dedicated line

Jun 20 03:01:59.399: Se0/0/0 PPP: Session handle[BA000009] Session id[9]

Jun 20 03:01:59.399: Se0/0/0 LCP: Event[OPEN] State[Initial to Starting]

Jun 20 03:01:59.399: Se0/0/0 LCP: O CONFREQ [Starting] id 1 len 10

Jun 20 03:01:59.399: Se0/0/0 LCP: MagicNumber 0x8D0EAC44 (0x05068D0EAC44)

Jun 20 03:01:59.399: Se0/0/0 LCP: Event[UP] State[Starting to REQsent]

Jun 20 03:01:59.407: Se0/0/0 PPP: I pkt type 0xC021, datagramsize 14 link[ppp]

Jun 20 03:01:59.407: Se0/0/0 LCP: I CONFREQ [REQsent] id 1 len 10

Jun 20 03:01:59.407: Se0/0/0 LCP: MagicNumber 0x73B4F1AF (0x050673B4F1AF)

Jun 20 03:01:59.407: Se0/0/0 LCP: O CONFACK [REQsent] id 1 len 10

Jun 20 03:01:59.407: Se0/0/0 LCP: MagicNumber 0x73B4F1AF (0x050673B4F1AF)

Jun 20 03:01:59.407: Se0/0/0 LCP: Event[Receive ConfReq+] State[REQsent to ACKsent]

Jun 20 03:01:59.407: Se0/0/0 PPP: I pkt type 0xC021, datagramsize 14 link[ppp]

Jun 20 03:01:59.407: Se0/0/0 LCP: I CONFACK [ACKsent] id 1 len 10

Jun 20 03:01:59.407: Se0/0/0 LCP: MagicNumber 0x8D0EAC44 (0x05068D0EAC44)

Jun 20 03:01:59.407: Se0/0/0 LCP: Event[Receive ConfAck] State[ACKsent to Open]

Jun 20 03:01:59.439: Se0/0/0 PPP: Phase is FORWARDING, Attempting Forward

Jun 20 03:01:59.439: Se0/0/0 LCP: State is Open

Jun 20 03:01:59.439: Se0/0/0 PPP: Phase is ESTABLISHING, Finish LCP

Jun 20 03:01:59.439: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/0,

changed state to up