Review Questions
Use this chapter and your practical troubleshooting knowledge and skills to answer the following questions. The answers are located in Appendix A, “Answers to Review Questions.”
| 1: | Why do interface resets occur? |
| 2: | True or false: The ISDN signaling protocol is LAPB for the D channel. |
| 3: | The modem control leads on show interfaces s0 are quite helpful for troubleshooting. DCD keeps changing state. What else on the interface statistics would you expect to be increasing? Look at Example 9-13 if you need to see a display of the modem control leads. |
| 4: | Your router has a native ISDN BRI port. Is this device a TE1 or TE2? |
| 5: | What is the difference between Multilink PPP and dial backup? |
| 6: | Use the first HDLC scenario as a guide. Can you spot the issue in the following output:
r3#
03:03:49: IP-EIGRP: Neighbor 192.168.9.18 not on common subnet for Serial0/3
03:04:03: IP-EIGRP: Neighbor 192.168.9.18 not on common subnet for Serial0/3
03:04:18: IP-EIGRP: Neighbor 192.168.9.18 not on common subnet for Serial0/3
03:04:32: IP-EIGRP: Neighbor 192.168.9.18 not on common subnet for Serial0/3
r5#show ip interface brief
Interface IP-Address OK? Method Status Protocol
BRI0 unassigned YES unset administratively down down
BRI0:1 unassigned YES unset administratively down down
BRI0:2 unassigned YES unset administratively down down
Ethernet0 unassigned YES unset administratively down down
Loopback8 5.5.5.5 YES manual up up
Serial0 192.168.9.18 YES manual up up
Serial0.101 172.16.8.6 YES manual deleted down
Serial1 unassigned YES unset administratively down down
r5#
03:04:01: IP-EIGRP: Neighbor 192.168.9.13 not on common subnet for Serial0
03:04:15: IP-EIGRP: Neighbor 192.168.9.13 not on common subnet for Serial0
03:04:29: IP-EIGRP: Neighbor 192.168.9.13 not on common subnet for Serial0
|
| 7: | Throughout the chapter you experienced multiple carrier transitions. What command is very helpful in helping you figure out the issues with this problem? |
| 8: | You have a high-speed Ethernet that is sending packets faster than the ISDN link can keep up with. How can you improve performance? |
| 9: | When are floating static routes appropriate? |
| 10: | When using the backup interface method to back up a circuit, do you place the backup interface command under the primary or secondary interface? |
| 11: | You are controlling the backup interface using the backup delay 10 60 command. What do the numbers 10 and 60 correspond to? |
| 12: | Your ISDN phone bill is a lot more than you expected, but you have interesting traffic set appropriately with an access list. It seems that when you finish transferring your files over the ISDN link, the link doesn't go down. It stays up until you manually bring it down. What did you forget? |
| 13: | Including synchronization and framing, what is the total bandwidth for ISDN BRI? |
| 14: | Can you use one 64 kbps B channel to handle backup for multiple T1s? |
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