Cisco CCNA 640-802 And CCENT Certification Exam Training – HDLC Configuration And Troubleshooting
Your CCNA and CCENT test results relies upon on recognizing how to configure and troubleshoot HDLC and PPP on Cisco routers, as nicely as recognizing the differences and similarities involving the two. Now we’ll just take a appear at HDLC and some primary router configurations, and in long run CCNA and CCENT certification test tutorials, we are going to take a look at PPP in element.
With a place-to-issue WAN url these as the subsequent, we have acquired two choices for encapsulation – HDLC and PPP. (HDLC, PPP, and Frame Relay do not run on LANs – you would not configure them on Ethernet interfaces.)
We’re not heading to examine HDLC for long, due to the fact you will find not a great deal to say about it – but what there is to say is really vital! The edition of HDLC employed by Cisco routers is the default encapsulation style on Serial interfaces, verifiable with the exhibit interface serial command. (Only the portion of this command’s output working with the PTP WAN url will be shown in this section.)
R1#demonstrate interface serial 1
Serial1 is up, line protocol is up
Components is High definition64570
World-wide-web tackle is 172.12.13.1/24
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
trustworthiness 255/255, txload 1/255, rxload 1/255
Encapsulation HDLC, loopback not set
R3#clearly show int serial1
Serial1 is up, line protocol is up
Components is Hd64570
Net address is 172.12.13.3/24
MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,
trustworthiness 255/255, txload 1/255, rxload 1/255
Encapsulation HDLC, loopback not established
At this issue, each partner in the PTP backlink can ping the other.
R1#ping 172.12.13.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.12.13.3, timeout is 2 seconds:
!!!!!
Success charge is 100 p.c (5/5), spherical-excursion min/avg/max = 36/36/36 ms
R3#ping 172.12.13.1
Variety escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.12.13.1, timeout is 2 seconds:
!!!!!
Accomplishment fee is 100 p.c (5/5), spherical-vacation min/avg/max = 32/35/36 ms
This particular version of the Large Details-Backlink Management encapsulation is Cisco-proprietary, a extravagant way of expressing “only Cisco routers fully grasp this encapsulation variety”. If a router at the finish of a PTP connection is jogging HDLC encapsulation, the remote associate in the website link should do so as well.
If one particular of the routers is running another encapsulation form, the bodily interfaces will still be up, but the line protocol will go down and IP connectivity will be misplaced. To illustrate, I’ll improve the encapsulation variety on R3’s Serial1 interface to the Stage-To-Place Protocol (PPP).
R3(config-if)#exit
R3(config)#int serial 1
R3(config-if)#encapsulation ppp
A couple seconds later, the line protocol goes down on R3.
2d04h: %SYS-5-CONFIG_I: Configured from console by console
2d04h: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1, modified condition to down
display interface serial 1 on both equally routers verifies that the physical interface is up, but the line protocol is down. IP connectivity is dropped.
R3#show interface serial 1
Serial1 is up, line protocol is down
R3#ping 172.12.13.1
Kind escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.12.13.1, timeout is 2 seconds:
…..
Achievements level is % (/5)
R1#exhibit interface serial 1
Serial1 is up, line protocol is down
R1#ping 172.12.13.3
Kind escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.12.13.3, timeout is 2 seconds:
…..
Achievement level is percent (/5)
The encapsulation mismatch has brought the line protocol down, and to provide it back again up, we basically need to make the encapsulation kinds match yet again. We are going to do just that in the subsequent installment of my distinctive Cisco CCENT / CCNA certification examination tutorial sequence!
