Cisco CCNA Exam Tutorial Five ISDN Details To Remember
Below is a MRR and PLR article in category Computers Technology -> subcategory Computer Certification.
Cisco CCNA Exam Guide: Five Key ISDN Details to Remember
Summary:
ISDN is a complex topic on the CCNA exam. Discover five common ISDN mistakes and learn how to avoid them, courtesy of Chris Bryant, CCIE
12933.
Keywords:
Cisco, CCNA, exam, ISDN, BRI, pass, tutorial, status, interface, dialer, profile, PPP
---
Mastering the CCNA exam requires understanding new technologies, and few are as detailed as ISDN. While some may consider ISDN outdated, many small to mid-size networks still use it as a backup for frame relay. Additionally, some networks rely on ISDN to connect spokes to hubs, making it essential for both the exam and real-world applications. Here are five common ISDN errors and how to avoid them.
1. Understand Dialer Map Statements
When using dialer map statements, ensure that the phone number you enter is for the remote router, not your local one. Think of it like calling a friend; you wouldn’t dial your own number.2. Don’t Forget the Broadcast Option
Always include the broadcast option in your dialer map command to enable routing protocol updates and hellos:```bash
R1(config-if)
dialer map ip 172.12.21.1 name R2 broadcast 5555555
```Without "broadcast," routing updates and hellos won’t traverse the line. This is also necessary for frame relay map statements.
3. Configure PAP Properly
PAP, a clear-text authentication scheme for PPP, requires additional setup with the `ppp pap sent-username` command. Remember, clear text is risky, but here's how to configure it:```bash
R1(config-if)
ppp pap sent-username R1 password CISCO
```4. Set Encapsulation to PPP
If you receive an error while configuring the sent-username, it’s because the default BRI line runs HDLC, not PPP. HDLC doesn’t support PAP or CHAP, so switch to PPP first:```bash
R1(config-if)
encapsulation ppp
R1(config-if)ppp authentication pap
R1(config-if)ppp pap sent-username R1 password CISCO
```5. Configure the ISDN Switch-Type First
Before anything else, set the ISDN switch-type. Without this, the line won’t come up regardless of avoiding other errors. Configure it with:```bash
R1(config)
isdn switch-type basic-ni
```Verify it with:
```bash
R1
show isdn status
```If you forget, the `show isdn status` command will remind you:
```bash
R1
show isdn status
No Global ISDN Switchtype currently defined```
ISDN is crucial for your CCNA preparation, and it remains relevant in many production networks. Pay close attention to details, practice debugging, and you’ll achieve your CCNA certification in no time!
You can find the original non-AI version of this article here: Cisco CCNA Exam Tutorial Five ISDN Details To Remember.
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