Quick VLANs and Loopback Int Question

WillTech105

Hello again all,

I got another question here --

How come I cannot move a loopback int into a VLAN?


I tried it on my 3550 and the "swichport access VLAN X" cmd isnt even supported. Googled it but couldnt find a good answer behind the theory as to why.

Any explination would be appreciated.
Thanks!

EDIT: Also, two other questions popped in my head while configuring my lab...

1. Is it not possible to hardcore an IP addr on a int on a switch? (ex: fa0/10)
2. You CAN assign a single int ex: fa0/20 in two VLANs at once. Is there any reason why one would want to assign a int to be in two different VLANs?
3. Anyway to encrypt the VTP password when one does a "show vtp password"? service password-encryption doesnt work.
4. During the VTP transfer between 2 switches, it appears the VLANs transfer OK but the Ports section is empty. Is this normal, or should the ints transfer over as well? Ex: VLAN 20 fa0/12 on Switch1 while Switch2 only has VLAN20 and empty Ports.

Thanks again!

jojopramos

i'll try to answer some of your questions:
1. Is it not possible to hardcore an IP addr on a int on a switch? (ex: fa0/10)

answer....
you can configure it on a layer 3 switch like 3560 via the command no switchport so that it will become a Layer 3 port

2. You CAN assign a single int ex: fa0/20 in two VLANs at once. Is there any reason why one would want to assign a int to be in two different VLANs?

answer....
one example is if you have an IP phone connected. so it should be switchport access VLAN # / and switchport voice VLAN #

3. Anyway to encrypt the VTP password when one does a "show vtp password"? service password-encryption doesnt work.

answer....
When you configure a VTP password, it is via MD5 digest. I will recheck this one on my 3560 btw.

4. During the VTP transfer between 2 switches, it appears the VLANs transfer OK but the Ports section is empty. Is this normal, or should the ints transfer over as well? Ex: VLAN 20 fa0/12 on Switch1 while Switch2 only has VLAN20 and empty Ports.

answer....
You need to assign each port to the VLAN of your choice based on the VLAN that you created. The VTP only propagates/transfer the VLAN no. and name and the interface should be manually assign a VLAN no. or you can assign it as a trunk.

on the loopback interface, you cannot do anything on this to be transfer to a certain VLAN.

jojopramos

Follow up to your query on VTP password protection, the command to hide the VTP password is to add the word hidden/secret. Example: switch(config)#vtp password Cisco hidden

WillTech105

jojopramos, I appciate you answering my questions.

Thanks again!

Forsaken_GA

WillTech105 wrote: »

Hello again all,

I got another question here --

How come I cannot move a loopback int into a VLAN?

It's considered a layer 3 port, so the layer 2 switchport commands won't work. Try turning a physical port (ie, fa0/1) into a layer 3 interface via the no switchport command, and then try putting it in a vlan. It won't allow you to do that either.

Forsaken_GA

WillTech105 wrote: »

2. You CAN assign a single int ex: fa0/20 in two VLANs at once. Is there any reason why one would want to assign a int to be in two different VLANs?

Erm, it's not normal for a layer 2 interface to be in two different vlans at the same time. How are you configuring this? A trunk can carry multiple vlans, but an access port is generally a member of one vlan at a time.