vlans and ip addresses

I have a large block of ip addresses on a lan. I am going to have one so called core switch (4506) and some 4503 on different floors home run to this core 4506 switch. currently DNS, DHCP are outside of this network. The 4506 core switch has 2 WS-X4306 (6 port GBIC modules). I want each GBIC to be on its own vlan.

Question is what ip address am i suppose to assign the vlans? All hosts get random DHCP addresses already assigned and I am not able to separate all the hosts per floor to a different vlan. I can only assign each floor (a 4503) to a different vlan.

Does this make sense?

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A VLAN should be treated like a real LAN. Each VLAN needs to be a different IP subnet.

Reply to
Barry Margolin

I am not sure i can change everyone's ip address.

Baisically we are assigned a subnet say /21 subnet. Gateway

The DHCP is outside of this network. Everyone within my net on all floors gets random ip addresses, 5th floor user might get, and another user on 5th floor might get Do I have to get all the hosts on each floor and have them grouped together into a closer subnet like say

5th floor - 4th floor - 10.10.185-10-

etc etc....

What about dynamic vlans?

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I've been scratching my head while reading various threads on vlans. In a nutshell, should you think of vlans just like a physical lan & subnets. Where and how do you place a DHCP server in a vlan environment or any other application server shared by the various vlans... Do you windup with a single arm router concept with the vlans talking to the required servers via a local router which in effect will increase the utilization of the router along with consuming more bandwidth for back & forth to the router.

Reply to
Phil Schuman

Then you need to make a flat network connecting all the floors.


I'm not familiar with them.

Like I said before, a VLAN acts just like a normal LAN. VLANs are a way to split up the segments connected to a switch, or a collection of switches, into separate broadcast domains. IP over Ethernet expects all the hosts in a subnet to be in the same broadcast domain.

There are some tricks you can play with proxy ARP that allow you to handle a few exceptions to this rule, but it's not really workable if everything is random, like you say.

If you use DHCP, I think you should be able to get rid of the randomness. I'm not really familiar with DHCP server configuration, but I assume most of them are able to assign addresses within the appropriate subnet, based on the information provided by the DHCP relay.

Reply to
Barry Margolin

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