VTP, vlan port assignments

Does VTP also transfer port assignments, or does it only tranfers the vlans themselves?

I am playing around in netsim, and if i set up a switch as vtp server and trunk link to a vtp client, the port assignments I establish on the vtp server will be passed to the client.

To me this seems like odd behavior, since every switch could potentially have different port assignments, why would vtp pass that information?

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Comments

mobri09

VTP does not transfer port assignments.

fonque

then is this a bug in netsim version that I am using? because it does this behaviour consistenly

mobri09

I just read a switching book by cisco and it stated VTP advertisements only transfer vlan database information not port information.

mikej412

mobri09 wrote:

VTP does not transfer port assignments.

mobri09 wrote:

I just read a switching book by cisco and it stated VTP advertisements only transfer vlan database information not port information.

fonque wrote:

then is this a bug in netsim version that I am using? because it does this behaviour consistenly

If it isn't operator error, then it sounds like a bug in netsim.

phreak

Hmmm...

In the simulator I am running (boson) the thing passes ports and vlan information.

On switchA I configured it as a VTP server with a domain and password. Created two vlans, 100 and 101 on this switch. I assigned the fa0/11 on the switch as a trunk pork (switchport mode trunk). I also added int range fa0/1 - 4 to switchport access vlan 100.

int range fa0/5 - 10 were vlan 101.

On the other switch, switchB, I set it as vtp client and matched the domain and password as switchA. Set int fa0/11 to switchport mode trunk and then checked the vlan brief. The switch now showed the vlans that were assigned.

Show run indicated that the ports 0/1 - 4 were on 100 and fa0/5 - 10 were 101. I did not configure ANY interfaces on the client switch.

mikej412

amd phreak wrote:

In the simulator I am running (boson) the thing passes ports and vlan information.

Bad Simulator! Bad! Bad!

Make sure you've upgraded to the "latest greatest version" and submit a bug report -- maybe they'll fix it in release 10.0

You might want to try creating the trunk first, configuring VTP, and then modifying the VLAN database, and then configure some ports into VLANs and see what happens (versus what really should happen).

Other things to try
-- save, close, and open and reload -- may magically work
-- clear the config on the 2nd switch and reload, and try the trunk & VTP configuration again and see what happens that time
-- beg, borrow, rent some rack time on real equipment

phreak

Yeah not worried about it.

If I need access I have plenty of gear at my disposal.

I thought it was interesting.

mikearama

Geez... could you imagine if VTP did that in a live environment? Damn, at my gig, there'd be hell to pay.

bighornsheep

lol...it wouldn't make sense for VTP to transfer port assignments, they would be different ports on different switches...the whole point is to group the ports LOGICALLY...

dtlokee

What would happen if a 24 port switch was the server and a 48 port switch was the client, oh no, I can only use the first 24 ports?

VTP only transfers the VLANs, names, status and other parmeters, but not the port assignments. VTP updates are only sent on trunk links to other switches.

fonque

thank you for confirming that im not crazy. I'm going to conclude this is indeed a bug.

And I know I am using an old version of netsim. Its like 5.something.
I will buy a better simulator when I go after the CCNP. No point in upgrading CCNA software since Im taking the test tomorrow.