VTP Advertisements Will Not Be Exchanged If the Trunk Between the Switches Is Inactive

VTP Advertisements Will Not Be Exchanged If the Trunk Between the Switches Is Inactive

* What is VTP?

–VTP allows a network manager to configure a switch so that it will propagate all VLAN configurations to other switches in the network.

–VTP advertisements will not be exchanged if the trunk between the switches is inactive.

–A switch can be a member of only one VTP domain at a time.

* What is the default VTP setting?

  • VTP Version = 1

–VTP version 1 is not compatible with VTP version 2. By default, Cisco Catalyst 2960 switches run version 1 but are capable of running version 2.

  • VTP Domain Name = null

–the switch does not belong to VTP domain.

–For a VTP server switch to participate in a VTP-enabled network, it must be a part of the same domain.

–When switches are in different VTP domains, they do not exchange VTP messages.

–VTP domain names are case-sensitive.

  • VTP Mode = Server
  • Configuration Revision = 0
  • VLANs = 1

* Based on all the variables and all the setting, here is what you need to know:

–Domain name is case sensitive.

–Switches with different domain name will not synchronize with each other.

–Version in the same VTP domain needs to be the same.

–Password must be the same between switches.

–Higher revision number switch will update lower revision switch, regardless whether it is a server or client.

–What can you do to reset the revision number?

* What are the 3 different modes of VTP?

- What are the capabilities and restriction of server mode?

- What are the capabilities and restriction of client mode?

- What are the capabilities and restriction of transparent mode?

How many domainds

* When you disconnect a Cisco switch that is in “VTP client mode” to the “VTP server mode” switch,

1) What happen to the VLAN information that is currently running on the client switch?

2) What happen to the VLAN information if the client switch is rebooted by the administrator?

* What is VTP Configuration Guidelines?

–Always reset the configuration revision number before installing a previously configured switch into a VTP domain.

–Configure at least two VTP server switches in your network.

–Configure a VTP domain on the VTP server.

–If there is an existing VTP domain, make sure that you match the name exactly.

–If you are configuring a VTP password, ensure that the same password is set on all switches in the domain.

–Ensure that all switches are configured to use the same VTP version.

–Create the VLAN after you have enabled VTP on the VTP server.

–VTP information is only exchanged on trunk ports.

* Make sure you understand all the intrigue interaction between switches running VTP.

  • The configuration revision number determines whether the configuration information received from another VTP-enabled switch is more recent than the version stored on the switch.
  • The default revision number for a switch is zero.
  • Each time a VLAN is added or removed, the configuration revision number is incremented.
  • Each VTP device tracks the VTP configuration revision number that is assigned to it.
  • Before adding a VTP client switch to a VTP domain, always verify that its VTP configuration revision number is lower than the configuration revision number of the other switches in the VTP domain.
  • A VTP domain name change does not increment the revision number. It resets the revision number to zero.

* You need to know how does VTP message send between switches (U, B, M)?

* What is VTP request advertisement? Which events will trigger a switch to send out the request advertisement?

  • Request advertisements are sent if:

–The VTP domain name has been changed

–The switch receives a summary advertisement with a higher configuration revision number than its own

–A subset advertisement message is missed for some reason

–The switch has been reset

  • When a request advertisement is sent to a VTP server in the same VTP domain, the VTP server responds by sending a summary advertisement and then a subset advertisement.

–The summary advertisement contains the VTP domain name, the current revision number, and other VTP configuration details.

–A subset advertisement contains VLAN information.

* What is VTP summary advertisement? Which events will trigger a switch to send out the summary advertisement?

  • The summary advertisement contains the VTP domain name, the current revision number, and other VTP configuration details.
  • Summary advertisements are sent:

Every 5 minutes by a VTP server or client to inform neighboring VTP-enabled switches of the current VTP configuration revision number for its VTP domain

Immediately after a configuration has been made

* What is VTP pruning? What is the purpose of VTP pruning?

  • VTP pruning prevents unnecessary flooding of broadcast information from one VLAN across all trunks in a VTP domain.
  • You only need to enable pruning on one VTP server switch in the domain.
  • Pruning is disabled by default.

* What is the purpose of the following commands show vtp status?

  • Use show VTP status command to verify the following:

–Configuration revision number has been incremented to 6.

–There are now three new VLANs indicated by the existing number of VLANs showing 8.

–Domain name has been changed to cisco1.

* What is the purpose of the following commands show vtp counters?

  • Use show vtp counters command to confirm that the advertisements took place

* Troubleshooting:

- If your switch VLANs mistakenly gets wiped out by the switch that has higher revision number, what do you have to do to restore all the previous VLANs?

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