VTPv2 Transparent Mode - Not forwarding VTP packets in different Domain

layer3 · ‎05-26-2008

Hi All,

I'm doing some testing in the Lab and have 3 x 3750's daisy chained together running VTP, with 802.1q trunks hardcoded.

SW1 <--> SW2 <--> SW3

SW1 and SW3 are in VTPv1 domain A and are both in 'Server Mode'. However, SW2 is in VTPv2 domain B and in Transparent mode.

According to the Cisco Doc VTP Version 2 (SW2) supports only one domain, and it forwards VTP messages in transparent mode without inspecting the version and domain name.

However, I am not seeing this happen. When I increment the revision number on SW1, I am not seeing the VTP updates propagate to SW3, and vice-versa.

Has anyone experienced this behavior? Any suggestions?

Thanks in advanced.

Mario.

mahmoodmkl · ‎05-26-2008

Hi

Unfortunately this not going to happen,u need to have the transparent switch in the same domain then it will forward the VTP messages.

Thanks

Mahmood

layer3 · ‎05-26-2008

Hi Mahmood,

Thats interesting... despite what the doc CD says about v2 Transparent mode, this will not work.

http://www.cisco.com/en/US/docs/switches/lan/catalyst3750/software/release/12.2_44_se/configuration/guide/swvtp.html#wp1035121

So basically the doc CD is incorrect?

Thanks.

Regards,

Mario.

bvsnarayana03 · ‎05-26-2008

Yes it does support but only in VTP v2. Check the version of VTP you are running.

Check "VTP version2 mode" in "sh vtp status".

layer3 · ‎05-26-2008

Hi bvsnarayana03,

Yes SW2 is already in VTP v2 Transparent mode, and is not passing VTP messages from SW1 and SW3 on. SW1 and SW3 are in a different VTP domain.

Thanks.

Mario.

bvsnarayana03 · ‎05-26-2008

I'm referring you to another link on similar discussion. Here it was tested & confirmed that things work as mentioned in doc.

http://forum.cisco.com/eforum/servlet/NetProf?page=netprof&forum=Network%20Infrastructure&topic=LAN,%20Switching%20and%20Routing&CommCmd=MB?cmd=display_location&location=.2cbe7b75

layer3 · ‎05-27-2008

Hi bvsnarayana03,

Thanks for the information.

However, I still have the issue. SW2 has VTPv2 mode enabled as per 'show vtp status'. When I change the VTP domain on SW2 to A (same as SW1 and SW3), and then increase the revision number on SW1, I immediately see VTP messages propagate to SW3. I am not seeing this behavior though when SW2 is in a different domain.

As for the link you referred me too... very interesting... Unless this issue is hardware/software depended? I tried the same setup with 3560's and still get the same result.

When I get access to the lab next week, I will span the trunk port from SW2 --> SW3 and see if VTP messages are being passed on. I'll let you know how that goes.

Thanks for your help.

Regards,

Mario.