vtp mode

[suthomas1]

Hello All,

Our network uses Client and server vtp. recently one of the solution designers from an IT intergrator suggested that we change all network switches including Core, distribution and access to transparent mode.

what is the real necessity of doing it all on transparent mode. Also, once on transparent, how will devices update vlan information.

for eg. if access switch 2 has a new layer2 vlan or core switch has a new vlan, how would that go across to all switches. Will everything need to be manually configured on each switch.

Please help me understand it better.

thanks

[Latchum Naidu]

Hi,

VTP transparent mode works much like server mode in that you can create, delete, or modify VLANs in the local VLAN database. The difference is that these changes are not propagated to other switches. In addition, the local VLAN database does not accept modifications from other switches. VTP transparent mode switches forward or relay information between other server or client switches. A VTP transparent mode switch does not require a VTP domain name.

Please rate the helpfull posts.
Regards,
Naidu.

[suthomas1]

Thanks Naidu. then my question will be, if i create a vlan 100 on Core switch, wil it propagate to other access switches?

Similarly if i only create a layer2 vlan in an access switch, will that new vlan progpagate to rest of network devices.

Thanks again.

[cadet alain]

Hi,

No it wont. VTP transparent is only relaying vlan infos from clients and servers but do not propagate their own infos so if all your switches are in transparent mode it's like you were not doing vtp anymore.

Regards.

Alain.

[Latchum Naidu]

Hi,

It will only pass VTP updates received by switches in Server Mode to other switches in the VTP management domain, but will not actually process the contents of these messages. When individual VLANs are added, deleted, or modified on a switch running in transparent mode, the changes are local to that particular switch only, and are not passed to other switches in the VTP management domain.

Please rate the helpfull posts.
Regards,
Naidu.

[Latchum Naidu]

Hi,

Adding to above, if a switch in transparent mode it wont participate in vtp domain and so called no use of vtp there.
In this case you need to manually create or delete vlans in other all switches.

Please rate the helpfull posts.
Regards,
Naidu.

[Joseph W. Doherty · Accepted solution]

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Posting

"what is the real necessity of doing it all on transparent mode."

Real necessity; none.  However, suspect why it was recommended was to avoid VLAN config "accidents", i.e. where adding a switch either has its VLAN information replaced or where it replaces all the other switches VLAN information (the latter can even happen with a VTP "client").

"Also, once on transparent, how will devices update vlan information.  for  eg. if access switch 2 has a new layer2 vlan or core switch has a new  vlan, how would that go across to all switches. Will everything need to  be manually configured on each switch."

How then is VLAN info updated, as others have noted, you need to change each switch's config, if it needs to "know" of that VLAN.  I.e. yes, manual switch configurations.

NB: you would also need to manually prune VLANs, if desired.

PS:

I've seen a switch added to a major Enterprise campus LAN where VTP unintentionally changed production switches VLANs; it wasn't pretty.  The Enterprise decided to migrate to transparent mode (or off mode, if supported) to avoid this happening again, but another option might have been to use VTP passwords.  This, I believe, would require a positive setting on a switch to allow it to participate in the VTP domain.  The problem with relying on just VTP domain name, is how VTP operates when VTP domain name is null/blank.

[smogra]

Hi,

Go through this link to understand the clear difference between the other modes and transparent mode:

http://www.cisco.com/en/US/tech/tk389/tk689/technologies_tech_note09186a0080094c52.shtml#vtp_modes

Server—In VTP server 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 and synchronize their           VLAN configuration with other switches based on advertisements received over           trunk links. VTP server is the default mode.

Client—VTP clients behave the same way as VTP servers, but you cannot           create, change, or delete VLANs on a VTP client.

Transparent—VTP transparent switches do not participate in VTP. A VTP           transparent switch does not advertise its VLAN configuration and does not           synchronize its VLAN configuration based on received advertisements, but           transparent switches do forward VTP advertisements that they receive out their           trunk ports in VTP Version 2.

Hope that helps.

Cheers

Sweta

p.s. please rate the answer if it was useful