I have been reading the Cisco Security Response Document that details the newly discovered vulnerabilities in VTP. http://www.cisco.com/en/US/customer/products/hw/switches/ps5528/tsd_products_security_response09186a00807335bc.html
The workaround for two of the three vulnerabilities is to apply a VTP domain password. I use VLANs and VTP to segment our network, so this password looks like it will need to be applied on my core 3550 and all of my access layer 2950s.
Passwords
You can configure a password for the VTP domain, but it is not required. If you do configure a domain password, all domain switches must share the same password and you must configure the password on each switch in the management domain. Switches without a password or with the wrong password reject VTP advertisements.
If you configure a VTP password for a domain, a switch that is booted without a VTP configuration does not accept VTP advertisements until you configure it with the correct password. After the configuration, the switch accepts the next VTP advertisement that uses the same password and domain name in the advertisement.
The question that I have is, how safe is it to apply a VTP domain password? I am able to apply this during a maintenance window, but I do not want to potentially bring down VTP and all of our infrastructure in the process. All of my switches reside on a management VLAN and I do not want to lose connectivity to all of these devices. During the VTP/VLAN implementation, we had an issue with VTP that caused us to lose connectivity to all of our 2950s, and I had to visit each one with a console cable. I do not want a repeat of that. Any guidance that you can provide will be much appreciated. Thank you.
