vtp configuration register issue

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Nov 15th, 2003
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is it right to say that

1. if a newly inserted switch vtp mode is either client or server, it could caused network problems if the configuration register is higher than the existing?

2. that the vtp revission number doesnt have anything to do with influencing the vlan configuration.

3. if the configuration register is the one influencing the vlan configuration, how can we clear or reset it.

i would apprciate it if anyone could suggest few things to do/precautions with vtp configuration before inserting it in a vlan environment.

Thanks a lot.

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robho Sun, 11/16/2003 - 22:11
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By default, the switch is set to VTP server and revision at 0. The revision only increases if you actually configure the switch. I can see it having problems if it was configured offline causing the Config Revision to be higher than the VTP server currently in the network ... and then installed in the network.

Are you referring to VTP version or Config Revision. VTP version has nothing to do with vlan config. Config Revision will increase when you modify the vlan configuration.

The configuration register has nothing to do with vlan config. It only determines how the switch will boot up.

Please refer to the Best Practices doc for VTP and other protocols


milan.kulik Tue, 11/18/2003 - 01:57
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I agree.

Just one additional "best practice":

You can clear the VTP revision number one a new switch before connecting it to your network.

Simply change the VTP domain name to "something_else" and back to "your_VTP_domain" on the switch. It will set VTP revision number to zero and you can connect the switch to the network without any problem.

VTP ver. 3 (just released) has another mechanism how to avoid this problem.

See http://www.cisco.com/univercd/cc/td/doc/product/lan/cat4000/8_2/confg/vtp.htm#1038950






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