Chapter 6's Review Questions
| 1: | On the 1900, portfast is enabled on the 10-Mbps ports and disabled on the uplink ports. Can you change this? If so, how? Give a practical example of using portfast. |
| A1: | Answer: Portfast is enabled by default on the 10-Mbps ports in the assumption that they are host ports on the 1900. It is not enabled on the 100-Mbps uplink ports (ports A and B) assuming they connect to another switch or server. The commands on the 1900 are as follows: menu, p for port, select a port, and then h for portfast mode. Refer back to Table 6-7 for portfast commands on other devices. All host ports should be enabled for portfast. Specific examples include a host that can't find a domain controller or a DHCP server or a Novell client who never gets a login screen. |
| 2: | What command outputs the following on a 2900 CatOS:* = Static Entry. + = Permanent Entry. # = System Entry. R = Router Entry.
X = Port Security Entry
VLAN Dest MAC/Route Des Destination Ports or VCs / [Protocol Type]
---- ------------------ ----------------------------------------------------
1 00-90-92-2a-76-9a 1/1 [ALL]
1 00-80-c7-aa-c8-87 1/2 [ALL]
1 00-50-04-df-5f-3c 1/2 [ALL]
1 00-d0-79-68-84-8d 1/2 [ALL]
1 00-b0-64-81-e3-00 2/3 [ALL]
|
| A2: | Answer: The command is show cam dynamic on a CatOS box. |
| 3: | What command outputs the following on an IOS-based switch:Dynamic Address Count: 7 Secure Address (User-defined) Count: 0 Static Address (User-defined) Count: 0 System Self Address Count: 37 Total MAC addresses: 44 Maximum MAC addresses: 8192 Non-static Address Table: Destination Address Address Type VLAN Destination Port ------------------- ------------ ---- -------------------- 0010.4ba5.ae50 Dynamic 1 FastEthernet0/12 0010.ffe5.17fd Dynamic 1 FastEthernet0/12 0010.ffe5.17ff Dynamic 1 FastEthernet0/12 0050.04df.5f3c Dynamic 1 FastEthernet0/1 0080.c7aa.c887 Dynamic 1 FastEthernet0/11 0090.922a.769b Dynamic 1 FastEthernet0/11 00b0.6481.e300 Dynamic 1 FastEthernet0/12 |
| A3: | Answer: The command is show mac-address-table on an IOS box. |
| 4: | Is a port receiving traffic if it is in the STP blocking state? |
| A4: | Answer: Yes, a port is receiving traffic if it is in the blocking state, but it does not learn source MACs or forward any frames. The port is blocked by STP as to not cause a loop at Layer 2. However, it must still listen for BPDUs so that it can automatically become active if another port or device fails. |
| 5: | What are the STP state transitions? |
| A5: | Answer: See Figure 6-6 for the following STP state transitions: disabled, blocking, listening, learning, and forwarding. Compare STP to RSTP in Table 6-6. |
| 6: | How do you view the speed and duplex settings on a router or IOS-based switch? On a CatOS-based switch? |
| A6: | Answer: See Table 6-7. show interface on an IOS based switch, and show port on a CatOS based switch. |
| 7: | It is common practice to use loopbacks for testing. Can you be sure that a loopback address is always up? |
| A7: | Answer: The following output shows sending the log to an internal buffer on r3, bouncing lo10 (shut/no shut), and then reviewing the log. This type of logging is quite helpful in troubleshooting and less overhead on the device than logging to the console. It clearly displays that it is possible to shut down a loopback.
r3#configure terminal r3(config)#line console 0 r3(config-line)#logging buffered r3(config-line)#interface loopback 10 r3(config-if)#shut r3(config-if)#end r3#show ip interface brief Interface IP-Address OK? Method Status Protocol ... FastEthernet2/0 192.168.5.97 YES NVRAM up up Loopback10 192.168.6.100 YES NVRAM administratively down down r3#show log Syslog logging: enabled (0 messages dropped, 0 flushes, 0 overruns) Console logging: level debugging, 69 messages logged Monitor logging: level debugging, 0 messages logged Buffer logging: level debugging, 7 messages logged Trap logging: level informational, 73 message lines logged Log Buffer (4096 bytes): 03:46:39: %SYS-5-CONFIG_I: Configured from console by vty0 (192.168.5.99) 03:46:55: %LINEPROTO-5-UPDOWN: Line protocol on Interface Loopback10, changed state to up 03:46:57: %LINK-3-UPDOWN: Interface Loopback10, changed state to up 03:46:57: %SYS-5-CONFIG_I: Configured from console by vty0 (192.168.5.99) 03:47:22: %LINK-5-CHANGED: Interface Loopback10, changed state to administratively down 03:47:23: %LINEPROTO-5-UPDOWN: Line protocol on Interface Loopback10, changed state to down 03:47:34: %SYS-5-CONFIG_I: Configured from console by vty0 (192.168.5.99) r3#!!!ouch someone can shut down a loopback r3#configure terminal r3(config)#interface loopback 10 r3(config-if)#no shut r3(config-if)#end r3#show ip interface loopback 10 Loopback10 is up, line protocol is up Internet address is 192.168.6.100/28 Broadcast address is 255.255.255.255 Address determined by non-volatile memory MTU is 1514 bytes |
| 8: | I issued the following show interface command on the 2900 CatOS box to view the management IP address and its parameters. What is the 192.168.5.111 address?sw2900> (enable) show interface sl0: flags=51<UP,POINTOPOINT,RUNNING> slip 0.0.0.0 dest 0.0.0.0 sc0: flags=63<UP,BROADCAST,RUNNING> vlan 1 inet 192.168.5.98 netmask 255.255.255.240 broadcast 192.168.5.111 |
| A8: | Answer: Do the math. 192.168.5.111 is the broadcast address for subnet 192.168.5.96/28. The mask is 240 in the last octet, which means 4 bits were borrowed. The lowest 1 bit is 16, which is the increment for the subnets. You are using subnet 96. The first address on the subnet belongs to the router, which is .97. If you add 16 to the subnet, the next subnet is 112. One less than the next subnet is the broadcast address for the current subnet. Remember that all the host bits are 1s for the broadcast address. |
| 9: | Encoded Address Recognition Logic (EARL) is an ASIC that works with the bus arbitration for packet transfers in a Catalyst 5000. Ethernet ports use a custom ASIC called __________. Other ports use a custom ASIC called __________. |
| A9: | Answer: Ethernet uses SAINT and other ports use SAGE. |
| 10: | You are at a host and attempt to telnet to a switch. The following message appears:Password required, but none set Connection to host lost. What's the issue? |
| A10: | Answer: No vty password has been set. Although a password is not required on the console, it normally is required for telnet access. This is because login is the default on vty lines. You can fix the issue by supplying a password or by removing the login on the vty lines with the no login command. |
| 11: | Assume your environment to be what it is now for the chapter scenario. On hosta you type the command tracert 192.168.5.103. How many hops to the destination? |
| A11: | Answer: Hops are router hops. Everything on this side of the router is on the same network hop (broadcast domain) although there are different collision domains. The following trace output illustrates the one hop:
C:>tracert 192.168.5.103
Tracing route to HOSTC [192.168.5.103]
over a maximum of 30 hops:
1 <10 ms <10 ms <10 ms HOSTC [192.168.5.103]
Trace complete.
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