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SWITCH Set 4

创建于: 2010-01-03 12:29:57          

Review Questions

The following review questions are taken from the current SWITCH curriculum. These review questions do not reflect the actual questions you will receive on the live certification exam. They are only meant to supplement your learning experience.

 

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评论 (9)
  • Brian

    Brian  说: 2010-09-16 12:11:13

    Aloha David,

    IAW the new SWITCH OCG, pages 196 and 197, there are 4 different port roles: Root, Designated, Alternate and Backup.? In addition, with RSTP you have three different port states: Discarding, Learning, and Forwarding.

    Based on the question and answers in which to choose from, alternate and backup are the correct answers.

    Regards,

    Brian

  • David Diaz

    David Diaz  说: 2010-09-16 03:58:14

    2. Which two are valid port roles in RSTP? (Choose two.)
    ???????? alternative port
    ???????? backup port

    ???????? listening port

    ???????? learning port

    Can someone help me confirm this isn't correct? With RSTP you only have:

    Root Ports

    Designated Ports

    Alternate Ports

    Output taken from a switch:

    VLAN0001
    ? Spanning tree enabled protocol rstp

    Interface??????? Role Sts Cost????? Prio.Nbr Type
    ---------------- ---- --- --------- -------- --------------------------------
    Fa0/6??????????? Root FWD 19??????? 128.6??? P2p
    Fa0/11?????????? Altn BLK 19??????? 128.11?? P2p
    Fa0/7??????????? Altn BLK 19??????? 128.7??? P2p
    Fa0/4??????????? Desg FWD 19??????? 128.4??? P2p

  • Brian

    Brian  说: 2010-06-28 19:43:18

    All,

    After taking the Set 4 quiz and reading the reviews regarding question #8, I did a little research on Cisco's website.? I thought about the question and came up with the following:

    Upon receiving a BPDU, What happens with each feature?

    BPDU Guard
    When configured globally, BPDU Guard is only effective on ports in the operational PortFast state. Reception of a BPDU, signals an invalid configuration and places the port in an err-disable state. When explicitly configured on a port, BPDU Guard shuts down a port that receives a BPDU.

    BPDU Filtering
    When configured globally, BPDU Filtering applies to all operational PortFast ports. Reception of a BPDU cause the port to immediately loses its operational PortFast status. When explicitly configured on a port, it does not send any BPDUs and drops all BPDUs it receives.? This can result in bridging loops as the port will ignore any BPDU it receives.

    To summarize, upon receiving a BPDU, BPDU Guard will block the BPDU and place the port into an err-disabled state, where as BPDU Filtering will ignore any BPDUs and return the port to its non-Portfast mode of operation.? Therefore, it would appear answers B and D should be correct.

  • aml28

    aml28  说: 2010-05-02 00:06:01

    It would be nice to have a correct explanation for each answer and verification of answers.? Doesn't look like anyone reviews these.

    Correct answers appear to be:

    - BPDUFilter ignores the BPDU, while BPDUGuard blocks the BPDU.

    (when bpdu filter is enabled on the interface, not global config mode, basically turning off stp on the port)

    - BPDUFilter turns the port into default mode (non-PortFast), while BPDUGuard sets the port to error-disable mode.

    (when bpdu filter is enabled in global config mode.)

    Other 2 options (1 and 3) are incorrect because bpdu filter does not error disable a port and bpdu guard does.? This behavior also makes the 3rd option incorrect (There is no difference upon receiving a BPDU. The difference is upon sending a BPDU.)? Regardless if BPDU Filter is enabled on the interface or in global config, it will either ignore or transition to normal port when it "RECEIVES" a bpdu whereas BPDU Guard will err-disable the port.

  • demandred64

    demandred64  说: 2010-04-16 20:34:04

    Yeah you are right.

  • Lars Arvidsson

    Lars Arvidsson  说: 2010-04-16 15:57:40

    The correct anwer to question 8 ought to be:

    8. What are two differences between BPDUFilter and BPDUGuard when receiving a BPDU?
    - There is no difference upon receiving a BPDU. The difference is upon sending a BPDU.
    - BPDUFilter turns the port into default mode (non-PortFast), while BPDUGuard sets the port to error-disable mode.

    "Use the spanning-tree portfast bpduguard default global configuration command to globally enable BPDU guard on ports that are in a Port Fast-operational state. In a valid configuration, Port Fast-enabled ports do not receive BPDUs. Receiving a BPDU on a Port Fast-enabled port signals an invalid configuration, such as the connection of an unauthorized device, and the BPDU guard feature puts the port in the error-disabled state."

    "Use the spanning-tree portfast bpdufilter default global configuration command to globally enable BPDU filtering on ports that are Port Fast-enabled (the ports are in a Port Fast-operational state). ..... If a BPDU is received on a Port Fast-enabled port, the port loses its Port Fast-operational status and BPDU filtering is disabled."

  • Qasem

    Qasem  说: 2010-04-13 04:03:32

    You are right. According to CCNP SWITCh 642-813 "official cetification guide ,page 182, the right answer should be the third in the list:

    - It moves ports into the STP loop-inconsistent state if BPDUs are not received on a nondesignated port.

  • Qasem

    Qasem  说: 2010-04-13 03:58:08

    Question 6)

    I think the phrase "after enabling MSTP mode in a global configuration" is not needed and confusing as the command to enable MSTP is provided as one of the two required for the correct answer.

    Switch (config)# spanning-tree mode mst

    and

    Switch (config)# spanning-tree mst configuration

  • demandred64

    demandred64  说: 2010-03-27 19:34:34

    Question 8) This is incorrect - see Lars post

    I think the answers should be

    There is no difference upon receiving a BPDU. The difference is upon sending a BPDU.

    and

    BPDUFilter ignores the BPDU, while BPDUGuard blocks the BPDU.

    "Both tools put the port into error-disable mode." is wrong because BPDU filter just filters BPDUs it doesn't change the state of the port.

    Question 9)

    ? It enables the blocking port to move to a forwarding state.

    is clearly wrong. This is what loopguard is trying to prevent