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CDP & LLDP Questions 2

September 20th, 2017 in SWITCH 300-115 Go to comments

Question 1

Explanation

Cisco Discovery Protocol Version 2 has three additional type, length, values (TLVs): VTP Management Domain Name, Native VLAN, and full/half-Duplex.

Question 2

Explanation

The default CDP timer (the frequency a router sends CDP packets) is 60 seconds and the hold time (the amount of time a receiving device retains the CDP information sent by other devices) is 180 seconds. In this case the question wants to ask about CDP timer. Therefore half of the default CDP timer is 30 seconds.

Question 3

Question 4

Question 5

Question 7

Explanation

The information contained in Cisco Discovery Protocol advertisements varies based on the type of device and the installed version of the operating system. Some of the information that Cisco Discovery Protocol can learn includes:
+ Cisco IOS version running on Cisco devices
+ Hardware platform of devices
+ IP addresses of interfaces on devices
+ Locally connected devices advertising Cisco Discovery Protocol
+ Interfaces active on Cisco devices, including encapsulation type
+ Hostname
+ Duplex setting
+ VLAN Trunking Protocol (VTP) domain
+ Native VLAN

Reference: http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/cdp/configuration/15-mt/cdp-15-mt-book/nm-cdp-discover.html

Question 8

Explanation

You must enable CDP on the switch port connected to the Cisco IP Phone to send the configuration to the phone (which includes the Voice VLAN to be used).

Question 9

Question 10

Question 11

Question 12

Question 13

Explanation

The information contained in Cisco Discovery Protocol advertisements varies based on the type of device and the installed version of the operating system. Some of the information that Cisco Discovery Protocol can learn includes:
+ Cisco IOS version running on Cisco devices
+ Hardware platform of devices
+ IP addresses of interfaces on devices
+ Locally connected devices advertising Cisco Discovery Protocol
+ Interfaces active on Cisco devices, including encapsulation type
+ Hostname
+ Duplex setting
+ VLAN Trunking Protocol (VTP) domain
+ Native VLAN

Type-Length-Value (TLV) fields are blocks of information embedded in Cisco Discovery Protocol advertisements. Information in advertisements varies, and the TLV frame format allows for extending advertisements when needed.

CDPv2 advertises IP Network Prefix TLV contains a list of network prefixes to which a sending device can forward IP packets. A prefix includes the interface protocol and the port number. For example, Ethernet 1/0. 

Reference: http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/cdp/configuration/15-mt/cdp-15-mt-book/nm-cdp-discover.html

Comments
  1. f
    September 28th, 2017

    q12
    cdp can share VTP information .
    i think E also correct . please advice !

  2. switchy
    October 22nd, 2017

    I think CDP only shows what VTP domain the other device belongs to but not exactly VTP information. I guess VTP has it’s own packets to send out and NOT use CDP packets to tag the information.

  3. MZI John
    November 19th, 2017

    Question 10
    Which two settings are part of a default LLDP configuration? (Choose two)
    A. The LLDP hold time is 60 seconds
    B. The LLDP global state is disabled
    C. The LLDP reinitialisation delay is 5 seconds
    D. The LLDP interface state is enabled
    E. The LLDP timer is 60 seconds
    Answer: B D
    I think the ANSWER D is not correct, Please see the bellow link on Default LLDP Configuration.
    https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750x_3560x/software/release/15-2_4_e/configurationguide/b_1524e_consolidated_3750x_3560x_cg/b_1524e_consolidated_3750x_3560x_cg_chapter_010011.html

  4. Jack
    November 26th, 2017

    hi does any one have an idea on CDP concepts,

    Which two statements about CDP are true? (Choose two)
    A. CDP uses a TLV to advertise the native VLAN
    B. CDP is not supported with SNMP
    C. CDP is supported on Frame Relay sub interfaces
    D. CDP runs on OSI layer 2
    E. CDP runs on OSI layer 1

    i am not sure if Answer C is correct or not , i could see in some of the website that answer C is correct.
    in this website we have A and D is correct
    kindly clarify my doubt.

    Thank You,
    Jack

  5. SwitchO
    November 26th, 2017

    @Jack CDP is Not supported on Frame relay.
    Trust me on this one.
    CDP will transit through the Frame Relay PVC carried by the FR switch. By default it’s disabled on FR interfaces, but you can enable it. Then the end point routers will see one another, but you won’t see the intermediate frame switch(es).
    Yes, CDP is layer-2. However, the frame switch is a frame switch. CDP isn’t frame-relay, so it will ignore it. Once a PVC is created, CDP will flow through it, but not before.

  6. Anonymous
    November 28th, 2017

    Default LLDP Configuration
    Feature
    Default Setting
    LLDP global state
    Disabled
    LLDP holdtime (before discarding)
    120 seconds
    LLDP timer (packet update frequency)
    30 seconds
    LLDP reinitialization delay
    2 seconds
    LLDP tlv-select
    Disabled to send and receive all TLVs
    LLDP interface state
    Disabled
    LLDP receive
    Disabled
    LLDP transmit
    Disabled
    LLDP med-tlv-select
    Disabled to send all LLDP-MED TLVs. When LLDP is globally enabled, LLDP-MED-TLV is also enabled

  7. TKasali
    December 2nd, 2017

    Default LLDP Configuration
    Default Setting

    LLDP global state : Disabled

    LLDP holdtime (before discarding): 120 seconds

    LLDP timer (packet update frequency): 30 seconds

    LLDP reinitialization delay: 2 seconds

    LLDP tlv-select: Disabled to send and receive all TLVs

    LLDP interface state: Disabled

    LLDP receive: Disabled

    LLDP transmit: Disabled

    LLDP med-tlv-select: Disabled to send all LLDP-MED TLVs. When LLDP is globally enabled, LLDP-MED-TLV is also enabled.

  8. Marcus
    December 3rd, 2017

    Hello, guys! Could you explain why Q10 answer D is correct and why Q12 answer C is correct? I tested CDP for Q12 with native VLAN mismatch in CPT and UNL. Yes, I get a notification every time, but CDP still works and I can see neighbor switch via ‘show cdp neighbors’.

  9. Addie
    December 3rd, 2017

    Question10 ans D is not correct as Cisco documentation says. So anybody bother to explain why D is correct?

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