No VTP updates

[bnorton916]

Using a network simulator.

2-2950 clean switches.

Configure trunk line between them.
Configure 1 as a vtp server the other as vtp client

The vtp server I setup 2 vlans, 20 and 30.

The second switch never gets updated.

I set-up a domain name on the vtp server switch.

Still no update on the other switch.

I set-up the same domain name on the second switch.

The second switch gets updated properly.

Now, I thought the second switch would automatically take the domain name if it didn't have one(I read this somewhere).

Is the simulator wrong or I am wrong?

Thanks,

Bill

btw good practice for me trying to figure what was going on

 

[unclerico]

yes, as long as you have a domain-name configured on a VTP server, a VTP client or other VTP server will assume that it is a member of that domain once it receives the first VTP advertisement. this is assuming you have no password configured and that you're running VTP v2.

I hate all Uppercase... I don't want my groups to seem angry at me all the time! =)
- ColdFlame (vbscript forum)

 

[VinceWhirlwind]

If you do a show vtp status on each switch before you configure the domain name, what do you get?

 

[bnorton916]

Too late now, I would have to reset. No big deal, I just wanted to confirm my thinking.

This simulator is a mixed blessing. On one hand, it makes me better(you always learn more when things aren't working quite right), but I don't want to pick up any bad habits.

Thanks,

Bill

 

[VinceWhirlwind]

A good habit would be to approach VTP with care. The first time I had a big network of hundreds of Cisco switches across dozens of sites I used to use VTP as a matter of course, without any second thought, and it was great, because I had 100% control of what went on on that network. Subsequently, I worked on Cisco networks where random people occasionally did random things and I learned that the best thing to do was set all the switches to VTP transparent and then not use VTP at all.

Configuring the domain name is a good thing to do.

Ultimately, your design should control where VLANs extend on your network, so you shouldn't use a dynamic process to have those VLANs extended. Also, individual VLANs should extend to as few switches as possible, and individual switches should have as few VLANs extended to them as possible. Cisco haven't quite got their heads around this concept yet, and the 1980's function-based use of VLANs is *still* persisting in academic and architecture documents despite this approach no longer being correct. This is probably the result of a disconnect between technically-literate staff and those who write higher-level documentation based only on a theoretical understanding of ethernet instead of a practical one.

 

[bnorton916]

Vince,

Thanks for the advice. VTP may not be used much on enterprise networks but I need to at least understand it for the CCNA exam.

I could see where VTP is nice in concept but would cause problems in larger networks.

Oh and thanks for your confirmation on my ethernet answer and while back. I was wondering if I had just completely missed the boat since no one replied.

You work as a network engineer somewhere Vince?

Bill

 

[bnorton916]

I should also say that I pulled 2-2950's out and the one did update its vtp domain. So the simulator was wrong which is what everyone suspected.

Bill

 

[VinceWhirlwind]

Bill, it's a bit disconcerting that a simulator fails to simulate properly. On the other hand, encountering broken things accelerates learning.

My tips for you are to resolve the following two ambiguities which are very common:
- between VTP "pruning" (pruning VTP updates) and VLAN "pruning" (pruning VLANs on/off trunks)
- the word "trunk" refers to a link where both sides are configured for dot1q ethernet tagging OR a "trunk" where two or more interfaces are joined in link aggregation (LACP/Etherchannel).

I never had a problem with VTP until I started sharing responsibilites in environments where there was, shall we say, less control over changes.

Yes, I have worked as a network engineer for the last 6 or 7 years.

 

[bnorton916]

Vince,

Do you ever use SNMP in your job?
Why or why not?

Bill

 

[VinceWhirlwind]

Yes, SNMP is good for monitoring, but you have to be aware of the security issues and choose your configuration carefully.

 

[bnorton916]

Sorry, I don't think my question was phrased correctly.

I am curious as to how you do/don't use SNMP being an network engineer.

When it comes to the actual SNMP protocol, I am very comfortable with how it works(any verison). But I don't get to see it in action on production environments so I was just curious.

Thanks,

Bill

 

[VinceWhirlwind]

Well, mostly, applications used for monitoring already know the strings to query to give me error count on an interface, or CPU load on a node, etc...

Sometimes you have to script it in when your application doesn't have the MIB for whatever it is you want to query.

I've also used SNMP to recover passwords once on a network where I couldn't access some of the switches.