VTP Mode and Service Config for HP and IBM Cisco Blade Switches
Posted by: Aaron Delp in Cisco, HP Blades, IBM Blades
Some time ago Scott Lowe wrote up a great article on how to set up link state tracking for Cisco switches on both IBM and HP Blades.
I have set up a number of the switches lately and I wanted to add two more commands that I consider default settings on the switch to make your life easier before deployment. You will want to check with the network admin once you are on-site and probably modify them again to meet customer requirements.
vtp mode transparent
no service config (on the HP Cisco 3020 switches)
VTP Mode Transparent will place the switches into a mode where they will not participate in the VTP Domain to pass VLAN information to other Cisco switches in your organization. This allows you to “sandbox” the switch at the customer site and make sure everything plays well before you place the switch in the VTP domain. This prevents VTP problems if your VTP number is higher than the customer’s number, which would push your VTP settings out to the rest of the organization, providing they didn’t change the default VTP domain name. Sounds crazy, but it can happen.
No Service Config on the HP Blade Cisco switches will disable the “smart” feature in the switch where it will broadcast for a TFTP service to configure itself. If you don’t want/need this feature, simply enter this command in the config and it will go away. You will know you have this feature turned on if you are getting the following error in the switch logs and console on a regular basis:
%Error opening tftp://255.255.255.255/network-confg (Socket error)
%Error opening tftp://255.255.255.255/cisconet.cfg (Socket error)
%Error opening tftp://255.255.255.255/3620-confg (Socket error)
%Error opening tftp://255.255.255.255/3620.cfg (Socket error)
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Hi Scott,
I’m not sure if its the way you explained VTP, but transparent mode will still forward VTP advertisements to other switches. It just won’t act upon them for itself.
So you have a VTP server then a VTP Transparent switch, then a VTP client (assuming Domain & Password match) then the client will still get VTP advertisements from the VTP server through the transparent server.
I was talking to a guy last week that always leaves 1 switch in transparent mode and duplicates his VTP server config to it manually so if something happens to his VTP server he can just switch his transparent into Server mode. If someone threw a rouge VTP server into the mix with a higher revision and set everyone back to only Vlan 1 he wouldn’t be screwed.
Maybe I didn’t understand what you were explaining. Love your blog, I learn a ton!
-Mike
Hey Mike! It’s Aaron by the way
You will find out very quickly that the extent of my Cisco knowledge doesn’t extend too far beyond the basic configuration of the switches for IBM and HP Blades. I’m sorry if it wasn’t clear in the way I presented it. I just wanted to make sure people out there that aren’t familiar with VTP make sure they don’t introduce a switch with a configuration that could harm an existing environment.
You are completely correct in your interpretation and I love the idea of “storing” the VTP on a switch that is in transparent mode. I will ask the Cisco guys in our company if they do this and I will certainly recommend this to clients!
Thanks again for coming by!
Aaron
I’ve been told that best practice is to power up the switch on the bench (in the chassis) without it being connected to the network and make sure that it is in client mode. Once you connect it to the network and join the VTP domain, you can change it to the proper mode as per design.
I know of one occasion where the VTP domain was stepped on by a new switch in server mode as it was introduced into an existing evironment. I don’t know how the engineer managed to do it but a certain major NY newspaper was not happy.
-Tim-
Tim! I’m honored!! I hope Alabama went well. Thanks for posting!
A comment from the old site: http://aarondelp.blogspot.com/2008/02/vtp-mode-and-service-config-for-hp-and.html
I have moved the comment over here and I will reply:
Anonymous said:
Hi Aaron,
Do you know if it’s possible to change the service config setting to look for a specific file on a specific server instead of broadcasting?
My response: Good Question! I’m not sure but I will check. My Cisco guy is actually at the hospital because his wife is having their first baby today. It may be a few days but I’ll get back to you.
- Aaron
Any word from your cisco guy on the service config setting?