cisco ccna exam objectives

cisco ccna exam objectives.state = OPENFrom line 5 of the above output, it is clear that the encapsulation is set to PPPo Next is the state of the LCP ( lepstate=OPEN) o The state OPEN indicates that the LCP has successfully completed parameter negotiation, allowing the data link layer to enter an active state. Then, there is the state of the NCP. In this example, only two protocols are transmitted over the PPP connection: IP (nep ipepstate = OPEN) and CDP (nep cdp state =OPEN) oIf one end is configured for PPP, and the other end is configured for another encapsulation type (e.g. HDLC), the state of the interface will be "up, lineprotocolisdown". If the physical and data link layer status of the interface is "up,lineprotocolisup", but there is no Layer 3connectivity, the problem may lie in the IP addressing of the two peers: the wrong address is used to perform the ping operation, or the addresses of the two peers are on the wrong subnet.The addresses of the two peers are located in the wrong subnet. *", above required:*If there is a problem at the data link layer after PPP is configured, use the following debug command to troubleshoot the connection.Router# debug ppp negotiation PPP protocol negotiation debugging is on Router# configure terminal Enter configuration commands, one per line. end with CNTL/Z. Router(config)# interface serial 0 Router(config-if)# no shutdown %LINK-3-UPDOWN: Interface SerialO, changed state to upppp: sending CONFREQ, type = 5 (CI_MAGICNUMBER), value = 4FEFE5 PPP SerialO: received config for type = 0x5 (MAGICNUMBER) value = 0x561036 acked PPP SerialO: state = ACKSENT fsm_rconfack(0xC021): revd id 0x2 ppp: config ACK received, type = 5 (CI_MAGICNUMBER), value = 4FEFE5 ipep: sending CONFREQ, type = 3 (CI_ ADDRESS), Address = 192.168.2.1 ppp SerialO: Negotiate IP address: her address 192.168.2.2 (ACK) ppp: ipcp_reqci: returning CONFACK. ppp: cdp_reqci: returning CONFACK PPP SerialO: state = ACKSENT fsm_rconfack(0x8021): revd id 0x2 ipep: config ACK received, type = 3 (CI_ADDRESS), Address = 192.168. 2.1 PPP SerialO: state = ACKSENT fsm_rconfack(0x8207): revd id 0x2 ppp: cdp_reqci: received CONFACK %LINEPROTO-5-UPDOWN: Line protocol on Interface SerialO, changed state to upIn this example, debug is enabled first, and then the serial interface is enabled. Note that the two connected routers go through a negotiation process: they first check each other's IP addresses (192.168.2.1 and 192.168.2.2) to make sure they are different; then they negotiate the protocols (ipcp_reqci and cdp reqci)o In this example, IP and CDP are negotiated, and upon successful completion of the negotiation, the data link layer enters the active state.To change the encapsulation of a serial interface to PPP, use the command encapsulation ppp. In the output of the command show interfaces, protocols with the status OPEN have been successfully negotiated. If there is a problem with LCP negotiation, you can use the command debug ppp negotiation to troubleshoot the problem.