Chapter 5's Review Questions
| 1: | How would a user complain to you about an incorrect frame type issue? |
| A1: | Answer: For an incorrect frame type issue, I would expect to hear things from the user such as, “I can't print,” “I can't get to my file,” “I don't see anything in Network Neighborhood,” “My screen says invalid drive specification,” “I don't have a drive F,” and so on. |
| 2: | What is the EtherType and SAP for Novell IPX? How does the receiving station recognize an 802.3 Novell-Ether frame? |
| A2: | Answer: EtherType is 8137, and
SAP
is e0. The checksum hex bytes 0xFFFF are for receiving station recognition. (See Figure A-4
and Figure A-5.)
|
| 3: | How do you know when an Ethernet network needs to be upgraded? |
| A3: | Answer: Yes, your users will tell you, but I hope you are one step ahead of that because you have been monitoring the load with a good network management program. You should be tracking the addition of multiple users, protocols, other devices, and all application requirements. Upgrading the bandwidth is always a good thing to do, but good use of switches to segment your existing environment into multiple collision domains assists in the cost of the upgrade process, too. Know your network and its utilization, throughput, and capacity. Look at your interface statistics and calculate the collision rate by dividing collisions by the output packets. This is a tough question to answer in just a few sentences, and obviously you should plan for upgrades. |
| 4: | What does the following error message indicate: “%CDP-4-DUPLEXMISMATCH:Full/half duplex mismatch detected”? |
| A4: | Answer: CDP detected a duplex mismatch between Cisco devices, but it is up to you to fix it. |
| 5: | Will communications occur if the port on one side of the link is set to full-duplex and the other side is set to half-duplex? How about if there is a speed mismatch? |
| A5: | Answer: Yes, it will probably work, but this situation of mismatched duplex settings is prone to performance issues. On the other hand, mismatched speeds will not communicate at all. |
| 6: | True or false: Fast Ethernet can carry more than 1500 bytes of data in the payload. |
| A6: | Answer: False. Unfortunately Fast Ethernet does not increase the data packet size for Ethernet. |
| 7: | What types of housekeeping traffic would you expect on the wire with Ethernet in a network similar to the chapter scenario? (Refer back to Figure 5-1.) |
| A7: | Answer: Routing protocol traffic such as the EIGRP hellos via multicast address 224.0.0.10, CDP updates, and keepalives at a minimum. |
| 8: | When should you clear the counters on an Ethernet interface? How do you clear the counters for interface e0? |
| A8: | Answer: Clear counters when you want to look at what is happening for a specific period of time or after fixing problems. Use the Cisco IOS command clear counters to clear all interface counters or the command clear counters e0 to clear just the counters for the e0 interface. |
| 9: | Compare DIX Ethernet to IEEE Ethernet |
| A9: | Answer: DIX Ethernet (or Ethernet II) uses a 2-byte type field to link to Layer 3. IEEE 802.3 Ethernet uses a valid length field but uses an IEEE SAP to point to Layer 3. (Refer back to Figure 5-3.) |
| 10: | What frame type carries CDP packets? How do you know? |
| A10: | Answer: CDP uses IEEE 802.3 frame format with a SNAP header. (Refer back to Figure 5-15.) |
| 11: | What command shows you the Layer 2 address for Ethernet on a Microsoft client? On a Cisco router? |
| A11: | Answer: Issue winipcfg or ipconfig /all on the client for the IP parameters and MAC address. Issue show interfaces [interface] on a Cisco router to see the MAC and other statistics. |
| 12: | Are collisions an issue in full-duplex Ethernet? Why or why not? |
| A12: | Answer: No. Collisions are not an issue in full-duplex Ethernet because the shared media is removed. A point-to-point connection, whether via a crossover cable or to a switch, is required to eliminate taking turns on the medium. |
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