vlan creation

[Arvind kumar]

can we have 2 or more VLAN's in the same LAN on the same subnet. I have to design vlan for my organisation. I have trouble in desinging the vlan for the same

[sourabhagarwal]

each VLAN has got it's own subnet. so you can have more than 2 VLANs in your LAN but each VLAN will have unique network or subnet if you want to communicate between VLANs.

hope this URL will give you more information.

http://www.cisco.com/univercd/cc/td/doc/product/software/ios113ed/113ed_cr/switch_c/xcvlan.htm

http://cio.cisco.com/univercd/cc/td/doc/product/lan/cat6000/122sx/swcg/vlans.htm#wp1026273

rate if it helps ...

[Anand Narayana]

it is not possible to have 2 vlan 's on the same subnet. because when you say 2 subnet, it means to different network. eg. 10.1.1.0/30 10.1.1.4/30.

so create vlans on different subnet or network.

hope this helps.

rate this post if cleared.

[Jon Marshall]

Hi

Just to clarify. It is perfectly possible to have more than one vlan on the same subnet, you just need a device that bridges the two vlans together.

This is how firewalls work in transparent mode and how load-balancers like the CSM work when in bridge mode.

Jon

[glen.grant]

Post is somewhat confusing as to what you are asking . In a good design you have 1 subnet address range per vlan such as 192.168.3.0/24 . Is it possible to have more than 1 subnet range per vlan or too make 1 subnet bigger , sure . You can either make the mask smaller which gives you more addresses per subnet or you can use secondary addresses on each assigned vlan which I do "not" advocate at all . This will work much better if you use 1 subnet address range per vlan and will make any troubleshooting a lot easier .

[Arvind kumar]

I have a flat network with 10.200.x.x with subnet mask 255.255.0.0

Now that accounts for Host 10.200.0.1- 10.200.255.254 with broadcast address 10.200.255.255. Now how could I design vlans in this case. I have to design 6 vlans. Thanks

[b.petronio]

The flat network must be not so flat, so u have to change it. And separate the range 0.0 - to 255.255 into 6.

Ex:

Subnet 1 : .0.0 - .41.255

Subnet 2 : .42.0 - .83.255

Subnet 3 : .84.0 - .125.255

Subnet 4 : .126.0 - .167.255

Subnet 5 : .168.0 - .209.255

Subnet 6 : .210.0 - .249.255

Loopback : .250.0 - .255.255

As u could easily see, each vlan has many addresses, so u can range it differently, according to ur needs.

I believe u must perform routing in this environment with the command ip routing in where they are created. (If MLS)

U need to pay attention if the hosts are addressing fixedly the ip, or having an DHCP to address them the ip.

If they are fixed... U have to change it one by one, accordingly with the right vlan.

If they are learning by DHCP, the 6 scope's address's must be created refering the range address's for host / subnet / and Default Gateway (IP from Vlan).

In the Vlan config u must specify that the broadcast for DHCP server is allowed, in order to perform the dhcp process.

ip helper-address (dhcp ip address).

Hope it helps,

Petr?nio