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2 Vlans Talking to each other

Unanswered Question

I am rookie when it comes to vlans so please keep this in mind.

What I am trying to accomplish is we have a network.

I want to create 2 vlans (to seperate traffic)

like have on 1 vlan and on another, can I do this and have them talk to each other and accomplish seperate broadcast domains with the vlan?

Thanks again

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r-godden Wed, 02/06/2002 - 01:42
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if you use vlans then you will need to route between


for 20 hosts per vlan use 27 bit mask this will divide your addresses into

0-31 32-63 etc

ejgonzalesiii Wed, 02/06/2002 - 08:45
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Yes this will work only if the router that you are using supports trunking.


paquino Fri, 02/08/2002 - 14:25
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1. It seems like the and the fall within the same IP subnet. In this case saparating these ip addresses with a vlan would totally isolate isolate the machines from one another.

vlan 1 10 .16 .1. 1-20

vlan 2 10 .16 .1. 21-40

255.255.0. 0

these are the same ip subnet.

2. If you meant the subnet and then they would be seperate broadcast domains but unable to talk to one another without a layer 3 interface for routing. So the answer is no you still wouldnt have full connectivity.

Lemme know if this helps


Paul Aquino


Cisco Systems

ryan.vaughn Mon, 02/11/2002 - 07:57
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I have done something similar to this, but not exactly what you are looking at.

I use Bay Networks Baystack 350T switches to seperate my vlans behind the router. Normally, I only vlan seperate subnets, but it should also work for vlans inside a subnet. We use this to run a single line into a building and seperate the tenant traffic via vlans to a single interface on a cisco router. I have never gotten a cisco catalyst switch to do the same thing I have seen with Baystack switches. I am not sure if this is because of functionality or inexperience on my part with catalyst switches (probably the latter of the two.)

I would NOT recommend taking this path however. If you want to seperate the 2 networks, I would recommend routing the two segments of the network between two interfaces on a router in two seperate networks. I just believe in presenting all options ;c)


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