VTP - Questions ?

[D Prasanna Kumar Reddy]

Hi All,

I have some questions against VTP. 

1> Does VTP breaks DTP if it fails to match VTP Domain name ?

2> Does Transparent Switch need to match VTP Domain name to pass VTP Updates ?

3> How we can make changes in VTP V 3 revision numbers ?

Thanks 

Prasanna Kumar Desireddy

[paul driver]

Hello

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@D Prasanna Kumar Reddy wrote:

Hi All,

I have some questions against VTP. 

1> Does VTP breaks DTP if it fails to match VTP Domain name ?

2> Does Transparent Switch need to match VTP Domain name to pass VTP Updates ?

3> How we can make changes in VTP V 3 revision numbers ?

Thanks 

Prasanna Kumar Desireddy

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1 -  No DTP is a different protocol to vtp
2 - Yes it does
3 - In vtp 3  only the vtp server set as primary can change vtp database

res

Paul

[D Prasanna Kumar Reddy]

Hi Paul,

Thanks for this.

1> Some where i read that it will break DTP relationship as loop prevention mechanism . 

3> I read that we cam make them Zero . .  But is it possible to increase/decrease number ?

Thanks 

Prasanna Kumar Desireddy

[Peter Paluch]

Hi Paul, Prasanna,

Regarding DTP and VTP - in fact, DTP messages carry the VTP domain name, and DTP negotiation will only be successful if both switches have the same VTP domain name, or at least one of the uses the empty (NULL) domain name.

This also means that if you rely on DTP to negotiate trunks, and you later change the VTP domain on one of your switches to a different value, DTP will fail, and your trunks will revert to access ports.

My personal explanation for this relation between DTP and VTP is that separate VTP domains are expected to have their own independent sets of VLANs, not shared with each other (that's obviously why someone decided to split the network into multiple VTP domains in the first place), and even same-numbered VLANs in the different VTP domains might be used for different purposes. Therefore, it would not be correct to bring up a trunk between switches in two different VTP domains automatically just because both switches speak DTP. Instead, if you really want to have a trunk between switches in VTP domains, you need to do it manually, fully under your control.

Best regards,
Peter

[paul driver]

Hello Peter

I am aware DTP is required to negotiation a dynamic trunk and VTP works in relation to update the vlan database via advertisements it exchanges between the trunks, But as DTP isn't required to create a trunk or populate the vlan database  I guess I may have made the assumption to the OP that the two protocols didn't work together which was incorrect.

res
Paul