Vlans - advice needed

[nero64]

Sorry this is long but please read.

I just started configuring switches last week in place of my colleague who is ill in hospital and won't be back to early Jan. Anyway I'm learning quickly. Which is good because I'm studying for my CCNA.

I was given the task of setting up a Vlan on a 3550 switch for our training room. The thing was I had to pull the existing 2948G switch out and use its settings and put them on the new 3550. The old one used a Bridge group but I figured that I have its IP so I could work it out.

Anyway just to make sure I got the config from another 3550(setup by my colleague) switch in the room which used Vlan 34. I noticed that all the ports were configured to use Vlan 1 which is the default but it uses the correct IP for Vlan 34, so you have the following:

Vlan 1 (10.96.34.135/25) --> all port interfaces. ie 34 is for Vlan 34 on our network.

So with the new 3550 I said ok I will just leave all the ports on the deafult Vlan 1 and assign it the IP 10.96.32.6/25 which is what the 2948G BVI 32 used.

Ok everything seemed fine. But I began thinking that both shouldn't be assigned to Vlan 1 so i tried to rechange the IP on vlan 1 for this second 3550 switch and create a Vlan 32 and assign the IP from above. I couldn't do it because it kept saying 10.96.32.0 is already assigned to vlan 1 even though I had changed the IP on Vlan 1 to somehing else.

Anyway in the end I just left it all to Vlan 1 and everything seems ok, but how can I remove the IP on Vlan 1 and set it up on the new Vlan 32. Or is ok to leave it on the defaults for both switches. I'm thinking that it doesn't matter because the IP's are different and Vlan 1 is just used locally by the switch not globally. Please someone give me some advice?

 

[vipergg]

You would have to delete the ip address on vlan1 before reassigning it to vlan 34 . This should be a simple change . If you change it to vlan 34 then you will have to change whatever ports you want in vlan 34 , on each user interface , it would have to read "switchport access vlan 34 " .

 

[nero64]

Hi,

I am setting up Vlan 32. What command would remove the IP 10.96.32.6/25 address on Vlan 1 so I could assign it to vlan 32.

 

[vipergg]

1 of 2 ways will get rid of it , conf t , int vlan 1 , no ip address or conf t int vlan 1 , default interface , enter . This will also get rid of it .

 

[computerhighguy]

it sounds like your buddy setup the port the switch is connected to as vlan 34. If so, then vlan1 on the your 3550 switch is the correct vlan. If your switches where sharing vlan information (i.e. on the same VTP domain, etc), then yes you would have to assign each switchport on your 3550 to vlan 34.

But it more sounds like the switch your 3550 is plugged into has been assigned vlan 34, making the entire 3550 switch on vlan 34. And since the switches aren't passing VLAN information, the IP address would be assigned to VLAN1 of the 3550.


It is difficult to explain, but I did it.


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[nero64]

It makes a little sense. Thanks for the input.

The cisco 3550 documentation is a good resource that I use but sometimes it doesn't tell you how to do the little things.

 

[baddos]

Depending on how your network is setup, you can either use that switch as a flat layer 2 switch (just use vlan1) or set it up to do VLAN trunking.

VLAN trunking using either 802.1q or ISL would allow multiple VLANs to use the same physical link to connect to another switch.

Is there a reason that the switch was replaced with a 3550? Because if you are just planning on leaving everything as VLAN1 it's a great waiste of cash since a 2950 would do the job just fine.

 

[firestormsp1]

If the 3550's share the same quirk as the 2950's, when you're dealing with your vtp and vlan's, we found we had to define the native vlan as well.....


Colin

 

[chieftan999]

If you are using ISL or 802.1Q, then it always makes sense to have a native VLAN assigned to allow traffic through that may not be tagged, or it will get dropped.


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