vlans and vtp

I need help on brushing up my vlans/vtp knowledge.

I have a router-on-stick topology with two switches running vtp in between.

(1) If I have subinterfaces on a router, {interface GigabitEthernet0/1.10 encapsulation dot1Q 10 and interface GigabitEthernet0/1.50 encapsulation dot1Q 50}, did I just create all necessary vlans? or do I need to manually create vlans in switches as well to match up? or do I only simply assign access ports to vlans on switches? { switchport access vlan 50 switchport mode access switchport voice vlan 10}

(2) Also, how do you save vtp settings as they don't show up in running config?

Thanks.

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Comments

networker050184

Routers do not participate in VTP. So you will need to create the VLANs on the switches. Depending on your switch and software assigning an access port to a VLAN may also create that VLAN int he database.

What settings are you talking about that do not show in the config?

sendalot

Right, I want router to handle inter-vlan communication for switches running vtp in between. For Catalyst 3550 and 2950, would assigning access port to a vlan create those in the databases? I have voice vlans for IP phone and data vlans and they all seem to be working fine. I was just wondering how I got by without creating vlans manually in the switches.

I'm talking about vtp configs I entered. Like "vtp mode server/client," etc.

networker050184

I'm not sure about your models and software versions. If you never manually created the VLANs and they were propagated via VTP then I'm assuming they were created automatically.

Those commands should show in the running config unless they are defaults.

DCD

It in the VLan.dat file in flash.

late_collision

sendalot wrote: »

(1) If I have subinterfaces on a router, {interface GigabitEthernet0/1.10 encapsulation dot1Q 10 and interface GigabitEthernet0/1.50 encapsulation dot1Q 50}, did I just create all necessary vlans? or do I need to manually create vlans in switches as well to match up? or do I only simply assign access ports to vlans on switches? { switchport access vlan 50 switchport mode access switchport voice vlan 10}

You will still need to create the VLANs on the switches or on a switch acting as a VTP Server, which will then propagate the VLAN database to the VTP Clients. However, these VLANs are not "active" on the switches until you assign 1 or more ports to that VLAN (access or trunk). Trunks will forward all traffic for all VLANs by default, so you may have to manually prune VLANs from a trunk link if you dont want that specific VLANs traffic to traverse the trunk. VTP Pruning can help solve this problem as well. For example, whats the point of forwarding VLAN 10's traffic to switch 2 if switch 2 does not have any ports assigned to VLAN 10?

The switches have no way to learn which VLANs are assigned from the router.

sendalot wrote: »

(2) Also, how do you save vtp settings as they don't show up in running config?

As mentioned above, after you exit VLAN configuration mode, the switch saves VLAN information to the vlan.dat file located on flash. Use the SHOW VLAN command to see which VLANs are defined, and the SHOW VTP STATUS to see how VTP is configured. Pay attention to the revision number of VTP when adding switches to your network, so you dont overwrite your VLAN database.

broli720

It says that you have CCNA and CCNA:Security. VLANS and VTP are pretty elementary stuff. I think you may need to bring the books out and do some review.

late_collision

broli720 wrote: »

It says that you have CCNA and CCNA:Security. VLANS and VTP are pretty elementary stuff. I think you may need to bring the books out and do some review.

VLANs in depth and VTP are part of the CCNP SWITCH exam...

xnx

I'd say VLANs and VTP are the first things you learn when you start doing cisco, definitely CCNA level stuff

EdTheLad

I doubt that sendalot has any of the certs listed on his profile, i would also doubt that he's studying for any certs. He uses this site as a means to do his day to day job. Look at his previous thread and you will see it's plainly obvious.

xnx

If the above is true then wow, people with 'paper certs' and those who fake their way into jobs make me sick. Some of us here know quite a bit and as much as our certs say so..

Obviosuly this might not be the case but i'm waiting to be corrected...