CCNA exam success depends on mastering many technologies that are new to you, and few exam topics have more details than ISDN. ISDN is not just for your CCNA exam studies, though. While ISDN is dismissed by many, the fact is there are many small and medium size networks out there that use ISDN as a backup for Frame Relay. Some of these companies have spoke networks that use ISDN to connect to their hub, and so it's a great idea to know ISDN configuration and troubleshooting for your career in the real world, as well as passing the CCNA. With that in mind, let's look at the five most common mistakes and how to avoid ISDN.
with the dialer map statements, remember that the phone number you put in the dialer map is the phone number of the remote router, not the local one. Look at it this way - if you want to call a friend on your mobile phone, do not you pick up the phone and dial your number!
Speaking of dialer map statements, do not forget the broadcast option all-important at the end of the command:
R1 ( config-if) #dialer map IP 172.12.21.1 name R2 broadcast 5555555
the router will accept the command without the "broadcast" option, but updates the routing protocol and greetings would not be able to travel on the whole line. (This command is also needed in the frame relay map statements to allow broadcasts and multicast to be transmitted.)
PAP authentication scheme in light of PPP and clear text is a bad idea. But if you have to set it up, do not forget that PAP requires additional configuration -the ppp pap sent-username command.
R1 (config-if) #ppp pap sent Username Password R1 CISCO
must set the encapsulation to PPP before using PPP subcommands
R1 (config if) #
the error message that we got during the sent-username command configuration is another important reminder - by default, a BRI line is running HDLC, PPP does not. Since HDLC does not allow us to use either PAP or CHAP, we'll have to set the link to PPP with the encapsulation ppp command.
R1 (config-if) #encapsulation ppp R1
R1 (config-if) the #ppp pap authentication
R1 (config-if) #ppp Pap Cisco posted username password
But before configuring any of this information, you should configure the ISDN switch-type. Post why? Because without the switch configuration-type, no matter that we avoid the other four errors - the line will not be up. Configure the switch-type with the "isdn switch-type", and then confirm with "status ISDN show".
R1 (config) #isdn switch-type basic-ni
R1 # show isdn
ISDN global Switchtype = basic-ni (output of this command cut here for clarity)
If you miss this part of the configuration, the output of waste of ISDN was show time in remembering!
R1 # show isdn status
**** No Global ISDN Switchtype currently defined ****
ISDN is an important part of your CCNA studies, and this knowledge it is still useful in production networks as well. Keep studying, notice the details, run these debugs, and you'll be a CCNA before you know it!
0 Komentar