| 1. | Put the following Ethernet standards in order of increasing bandwidth: 802.3z 802.3ae 802.3 802.3u
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| Answer: | c, d, a, b |
| 2. | What benefits does switched Ethernet have over shared Ethernet? |
| Answer: | Switched Ethernet ports receive dedicated bandwidth, have a reduced collision domain, and show increased performance because of segmentation or fewer users per port. |
| 3. | When a 10/100 Ethernet link is autonegotiating, which will be chosen if both stations can support the same capabilities10BASE-T full duplex, 100BASE-TX half duplex, or 100BASE-TX full duplex? |
| Answer: | 100BASE-TX full duplex will be chosen because it has the highest autonegotiation priority and is common to both end stations. |
| 4. | How many pairs of copper wires does a 1000BASE-T connection need? |
| Answer: | Four pairs |
| 5. | A switch port is being configured as shown here. What command is needed next to set the port to full-duplex mode? Switch(config)# interface fastethernet 0/13 Switch(config-if)#
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| Answer: | Enter the command duplex full at the prompt. |
| 6. | If a full-duplex Gigabit Ethernet connection offers 2 Gbps throughput, can a single host send data at 2 Gbps? |
| Answer: | No, a full-duplex Gigabit Ethernet connection allows only 1 Gbps simultaneously in each direction across the link. |
| 7. | Which GBIC would you use for a connection over multimode fiber (MMF)? |
| Answer: | You could use either a 1000BASE-SX or a 1000BASE-LX/LH. |
| 8. | A Category 5 cable having only pins 1,2 and 3,6 has been installed and used for a Fast Ethernet link. Can this same cable be used for a migration to Gigabit Ethernet using 1000BASE-T GBICs, assuming that the length is less than 100 m? |
| Answer: | No. 1000BASE-T requires all four pairs of wires to be present. |
| 9. | A Catalyst 3560 switch port has been configured for 100 Mbps full-duplex mode, but a link cannot be established. What are some commands that you could use to investigate and correct the problem? |
| Answer: | To see the current state of one or more ports, you could use the show interface command. This would show the ports' speed and duplex modes, and whether a link has been established. One reason the link is not established could be that the port is shut down or disabled. To enable the port, use the no shutdown interface-configuration command. Because the port has been set to 100 Mbps full-duplex mode, it is possible that the end station can support only 10 Mbps at half duplex. Therefore, set the port for autonegotiate mode with the speed auto and duplex auto commands. Otherwise, you could set the port to a fixed speed and mode that would match that of the end station. |
| 10. | The 10-Gigabit Ethernet is backward-compatible with other forms of Ethernet at Layer _____ but not at Layer _____. |
| Answer: | 10-Gigabit Ethernet is backward compatible with other forms of Ethernet at Layer 2 but not at Layer 1. |
| 11. | What one switch command will select Fast Ethernet interfaces 4/1 through 48 for a common configuration? |
| Answer: | interface range fastethernet 4/1 48 (Don't forget spaces around the dash.) |
| 12. | What is the purpose of a GBIC? |
| Answer: | A GBIC is used as a modular medium-independent connection for Gigabit Ethernet. A switch with a GBIC port will accept GBIC modules that support various network media types. Changing network media cabling requires only a low-cost GBIC module change. |
| 13. | Suppose you need to apply several different common configurations to Fast Ethernet interfaces 3/1 through 12, 3/34, 3/48, and 5/14 through 48. What commands are needed to create an interface macro to accomplish this, and what command would apply the macro? |
| Answer: | define interface-range mymacro fastethernet 3/1 12, fastethernet 3/34 48 , fastethernet 5/14 48 interface range macro mymacro
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| 14. | If a switch port is configured with the speed 100 and duplex full commands, what will happen if the PC connected to it is set for autonegotiated speed and duplex? Now, reverse the roles. (The switch will autonegotiate, but the PC won't.) What will happen? |
| Answer: | When the PC attempts to autonegotiate the link settings, it will detect the switch port's speed of 100 Mbps. However, the duplex cannot be detected without a two-way information exchange, so the PC probably will fall back to half duplex. The results are similar when the roles are reversed because the switch will decide on 100 Mbps half duplex. In either case, a duplex mismatch will occur. |
| 15. | By default, what will a switch do if one of its ports has a serious error condition, and how can you tell when this has happened? |
| Answer: | By default, every possible error condition is detected on every port. If any one of these conditions occurs, the port automatically will be shut down in the errdisable state. The show interface status err-disabled command shows a brief summary of all ports in the errdisable state. |
| 16. | What port speeds can you assign to a UTP Gigabit Ethernet switch port? Consider both 1000BASE-T GBIC and native RJ-45 copper switch module ports. |
| Answer: | A 1000BASE-T GBIC is fixed at 1 Gbps, whereas switch modules with UTP Gigabit Ethernet ports can be 10 Mbps, 100 Mbps, or 1000 Mbps. |
| 17. | What command can you use to make sure that no switch ports automatically are shut down in an errdisable state for any reason? |
| Answer: | Use the no errdisable detect cause all interface-configuration command. Remember that all causes are enabled by default, so you must disable all causes first. |
| 18. | Suppose you commonly find that switch ports are being shut down in errdisable because users are making their connections go up and down too often. Thinking that this might be the result of odd PC behavior, you would like to visit each user to troubleshoot the problem; however, this is a minor error and you don't want to inconvenience the end users too much. What commands can you use to have the switch automatically re-enable the ports after 10 minutes? Make sure a flapping link will be recovered automatically in this time frame. |
| Answer: | errdisable recovery interval 600 errdisable recovery cause link-flap
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| 19. | Look at the following show interfaces output. Does the high number of collisions indicate a problem? Why or why not? FastEthernet0/6 is up, line protocol is up Hardware is Fast Ethernet, address is 000a.f4d2.5506 (bia 000a.f4d2.5506) Description: Front Office PC MTU 1500 bytes, BW 10000 Kbit, DLY 1000 usec, reliability 255/255, txload 1/255, rxload 1/255 Encapsulation ARPA, loopback not set Keepalive set (10 sec) Half-duplex, 10Mb/s input flow-control is off, output flow-control is off ARP type: ARPA, ARP Timeout 04:00:00 Last input never, output 00:00:00, output hang never Last clearing of "show interface" counters never Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0 Queueing strategy: fifo Output queue :0/40 (size/max) 5 minute input rate 0 bits/sec, 0 packets/sec 5 minute output rate 0 bits/sec, 0 packets/sec 1321140 packets input, 227738894 bytes, 0 no buffer Received 13786 broadcasts, 0 runts, 0 giants, 0 throttles 1 input errors, 1 CRC, 0 frame, 0 overrun, 0 ignored 0 watchdog, 42 multicast, 0 pause input 0 input packets with dribble condition detected 87798820 packets output, 2662785561 bytes, 1316 underruns 6 output errors, 406870 collisions, 3 interface resets 0 babbles, 0 late collision, 19458 deferred 0 lost carrier, 0 no carrier, 0 PAUSE output 1316 output buffer failures, 0 output buffers swapped out
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| Answer: | Yes, this probably would be normal, considering that the interface is set for 10 Mbps half duplex. Collisions are to be expected on a link with shared bandwidth; in this case, the link is part of a collision domain. If the link were showing full duplex at any speed, collisions never should be detected. |
