VTP: CONCEPT: WHAT, MODES, KEY POINTS?


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REFERENCE

UNDERSTANDING VTP 

http://www.cisco.com/c/en/us/support/docs/lan-switching/vtp/10558-21.html

CONFIGURING VTP

http://www.cisco.com/c/en/us/support/docs/lan-switching/vtp/98154-conf-vlan.html#understand

TROUBLESHOOTING VTP

http://www.cisco.com/c/en/us/support/docs/lan-switching/vtp/98155-tshoot-vlan.html

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TOPICS

WHAT IS VTP?

VTP MODES

KEY POINTS

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WHAT IS VTP?

VTP is simply method of managing VLAN’s

In a network, Different VTP domains are formed. Different VTP domains cannot communicate.

In a single VTP domain, switches are given different roles

Roles are Server Mode, Client Mode, Transparent Mode

Depending on the role, switches functionalities are different

Let’s discuss different roles in next section

 

COMMAND TO SET VTP DOMAIN NAME

Router(vlan)#vtp domain domain-name

 

VTP RECOMMENDATIONS

All switches must have the same the VTP domain name, unless the network design insists for different VTP domains

All switches in a VTP domain must run the same VTP version

All switches in a VTP domain has the same VTP password

All VTP Server switch(es) should have the same configuration revision number and it should also be the highest in the domain.

 

COMMAND TO CHECK VTP DETAILS

ABC_6513_2#sh vtp status
VTP Version                     : 2
Configuration Revision          : 117
Maximum VLANs supported locally : 1005
Number of existing VLANs        : 142
VTP Operating Mode              : Server
VTP Domain Name                 : Call_Center
VTP Pruning Mode                : Disabled
VTP V2 Mode                     : Disabled
VTP Traps Generation            : Enabled
MD5 digest                      : 0xA6 0x80 0x33 0x46 0x1D 0x63 0x28 0xAD
Configuration last modified by 10.144.2.1 at 2-28-12 14:09:22
Local updater ID is 10.144.2.2 on interface Vl2 (lowest numbered VLAN interface found)

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VTP MODES

SERVER MODE

IN this mode, you can create, modify, and delete VLANs and specify other configuration parameters, such as VTP version and VTP pruning, for the entire VTP domain. VTP servers advertise their VLAN configuration to other switches in the same VTP domain. Simply, it gives one point of managing VLAN for the whole VTP domain

Whatever are the changes made on Server Mode in terms of VLAN gets replicated to all the other switches.

When changes are made, revision number gets incremented. By comparing Revision number on every switch in the network, switches update their database. Higher revision number takes precedence

 

CLIENT MODE

When it gets update from Server Mode switch,  Client Mode update itself and passes information to other switches

we cannot do any changes in the client mode. Switch will not allow and give error message

 

TRANSPARENT MODE

When it gets update from Server Mode switch, Transparent Mode do not update itself and passes information to other switches ,or simply act as Transparent

Whatever are the changes made on Transparent Mode, changes do not get replicated to any other switch.

 

OFF MODE(configurable only in CatOS switches)

In the three described modes, VTP advertisements are received and transmitted as soon as the switch enters the management domain state. In the VTP off mode, switches behave the same as in VTP transparent mode with the exception that VTP advertisements are not forwarded.

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KEY POINTS

There can be more than one Server Mode Switch, no one is primary or secondary. Having more than one Server Mode switch means having more than one point of managing VLAN’s, in a network

 

Default mode of switch is : Server Mode

 

New switch must be connected to the network in Client Mode and Revision Number=0

How to make Revision number=0?

Change VTP domain name to any bogus name(fake name) and then again change to required VTP domain name

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