VTP Version 1 vs version 2

[Network Learner's]

Hi all,

Can anyone tell me what is the major difference between VTP version 1 and version 2 apart from consistency check, token ring support in version 2.

[Joseph W. Doherty]

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@Network Learner's wrote:

Hi all,

Can anyone tell me what is the major difference between VTP version 1 and version 2 apart from consistency check, token ring support in version 2.

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Also the differences in transparent mode operation.

Possible useful:

https://journey2theccie.wordpress.com/2019/02/25/vtp-versions/

https://www.networkbulls.com/ask/what-is-different-between-vtp-v1-vtp-v2

https://www.cisco.com/c/en/us/support/docs/lan-switching/vtp/10558-21.html#toc-hId--1479613478

https://notes.networklessons.com/vtp-versions

[MHM Cisco World]

the points you mention is big different between two ver. 
MHM

[Joseph W. Doherty]

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@MHM Cisco World wrote:

the points you mention is big different between two ver. 
MHM

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Very true, although certainly support for token-ring is a huge difference, possibly, now a days, not a whole lot of V2 demand to support token-ring LANs.

Personally I would think the difference in transparent mode handling might be a more important difference, but that assumes you bother to use transparent mode, relaying VTP, at all (especially as current VTP V1/2 implementations should also now support the off mode).

Between the potential "accidents" that can easily happen with V1/2 and L2 domains often are now much smaller due to L3 switches, perhaps V1/2 differences, in practice, are possibly moot.

Overall, I think many today prefer to avoid using any VTP.  I.e. avoiding V1/2 for "safety" reasons, and avoiding even V3, as, again, large number of switches sharing the same VTP database, is just not as relevant in modern L3 switch environments.

[Network Learner's]

@Joseph W. Doherty 

i think now even version 1 will forward VTP advertisements in transparent mode even if the version or domain or both mismatched.

I just checked this in packet tracer.

[Joseph W. Doherty]

I just checked this in packet tracer.

Be very, very careful accepting PT results for correct functioning especially dealing with advanced nuanced details of feature or protocol operation.

In other words, PT behavior is often "buggy".

What you might try is doing the same on real hardware and/or CML.

[MHM Cisco World]

I never try before' but I think you are right.

I read somewhere that v2 transparent SW can forward vtp regardless vtp message version' where v1 drop it.

For your lab did you try use v1 to check that?

MHM

[Network Learner's]

@MHM Cisco World I checked this in packet tracer and as per @Joseph W. Doherty PT behaviour can also be a buggy.

Iam going to check this in eve or pnet lab.

Will keep you posted.

[Joseph W. Doherty]

It will be interesting what you find.

Interestingly, the Cisco link, I provided earlier, only mentions token-ring, by name, support as a V2 difference.

I have a copy of CML, but my PC doesn't have the resources to spin up a 9k switch.  So, I look forward to what you find.

[Network Learner's]

@Joseph W. Doherty checked this in EVE-ng as well and same result.

Switch -1 In VTP version 2 - switch 2 in vtp-version-1 and then switch-3 in vtp-version-2.

what ever  vlans I am creating in switch-1 will be replicated in switch-3.

[Aref Alsouqi]

What do you see on switch 2 when you issue the command "show vtp status"? also, which swtich is configured as the VTP server? I think what is happening here is that the server switch sends the VTP version number (in your case would be version 2) to the other switches, and because the other switches are capable to run version 2 they switch from version 1 to version 2 capable devices.

[Network Learner's]

Hello @Aref Alsouqi 

Thanks for taking your time on this post.

My lab scenerio.

Switch 1- Server switch with version 2.

Switch 2 - Transparent mode with Version 1.

Switch 3 - Client Mode with Version 2.

as per theory VTP version 1 in transparent mode will check version and domain name before forwarding VTP advertisements, but for Labs/practical this statement seems to be wrong.

either of the version can send a VTP advertisements in transparent mode.

Note :- if we have Domain name different between server and transparent mode ( any of the version will drop VTP packets).

Let me know if my understanding is wrong.

[Aref Alsouqi]

You're welcome. Yes, that is the theory and I agree with you. However, as I mentioned in my previous post, I think in your case what you are seeing is due to the fact that switch 1 sends the version number of VTP which is 2 in this case to switch 2, and as a result switch 2 moved to VTP version 2. I can't exactly remember how the "show vtp status" command output looks like, but I think in the output if would show you a hint of that.

[Aref Alsouqi]

Also, another difference between version 1 and 2 when it comes to the advertisements is that version 1 in theory checks both the configured domain and version, while version 2 checks only the domain I think.