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New Member

3560 -----> 6509 VTP - Domain - Password

I introduced a new 3560 into a client network using 2 SFP modules on the 3560.

So there were 2 fiber links from the 3560 to the 6509. As soon as the 2 connections were put on the same VLAN it brought down the client's entire switch, because all VLANs from the 3560 overwrote the 6509.


We believe the 3560 had a higher revision number and overwrote the 6509, but don't understand how this happened because the 6509 had a domain and password set up on the 6509 for the VTP.

The 3560 had no domain and password.


My question is this possible? How could the 3560 overwrite the VLAN if it did not have a domain or password to the 6509?


Re: 3560 -----> 6509 VTP - Domain - Password

don't know about the password , the 3560 does not need a vtp domain name , if it sees one from the 6509 it will inherit that domain name and if the revision number as you said is higher then we all know what happens which why you always clear everything before configuring a switch , set it to transparent then set it to client and that should never happen.

New Member

Re: 3560 -----> 6509 VTP - Domain - Password


Dynamic Trunking Protocol (DTP) sends the VTP domain name in a DTP packet. Therefore, if you have two ends of a link that belong to different VTP domains, the trunk does not come up if you use DTP. In this special case, you must configure the trunk mode as on or nonegotiate, on both sides, in order to allow the trunk to come up without DTP negotiation agreement.

So if you have manually configured the trunk port and the new switch has higher revision number will overwrite the old switch VLAN information.. and probably that is exactly what happened in your case.

Please rate if this answers your question.