Combination of Managed Switch with Unmanaged switches

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Mar 26th, 2008
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I have two 3750G-24PS switches and three unmanaged switches.I have configured VLAN's (15 nos.) in 3750 .Is it possible for me to use those three switches for all VLAN or I have to use separate switches for each VLAN . Please help me out .



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shrikar.dange Wed, 03/26/2008 - 01:25
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Hi,


It all depends on you!!Eighther way is possible.It more precisely depends on your network design and recuirement.If you can elaborate it in little depth then you will get some helpfull replies by the experts.


Regards,


shri

mahendra.alhat Wed, 03/26/2008 - 01:38
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Hi,

Consider I have 4 VLAN's and three unmanaged switches with 48 ports. I have 15 machines in each VLAN .Can i use same switches for 4 VLAN's or 4 switches foe 4 VLAN. If i use same switches will it create any problem in network like bandwith uses ,brodcast etc.Please help me.

Jon Marshall Wed, 03/26/2008 - 01:43
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Again, it depends on what you want to do. You can have a vlan per switch if you want and connect each switch to the 3750 on a different vlan and then have the 3750 route between vlans.


It really can be done in a number of ways ie. the one above and the one in previous post. Bandwidth problems could come in if you have one vlan that generates a lot of traffic, if so it may be better to spread that vlan across all 4 switches but then you would need to add config to unmanaged switches - you see why it's difficult to give a definitive answer ?


Jon

mahendra.alhat Wed, 03/26/2008 - 02:23
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Problem is what those three switches are unmanagable i can't config them i have caonfigured routing in those two 3750 switch(clustered).If i put two different vlan machines in single unmanaged switch with two cross cables will it create any prioblem???


Jon Marshall Wed, 03/26/2008 - 01:26
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Hi


To use the same vlans on all switches you would need to


1) Connect the switches via 802.1q trunks

2) Either configure the vlans manually on each switch (VTP transparent)


or


3) Set your 3750 with the vlans on it to be a VTP server and configure your other switches to be VTP clients.


However this would require some config on the unmanaged switches. So when you say unmanaged what exactly do you mean ?


Jon

Joseph W. Doherty Wed, 03/26/2008 - 04:03
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"Is it possible for me to use those three switches for all VLAN . . ."


Usually not.


". . . or I have to use separate switches for each VLAN"


Usually yes. (The 3 unmanaged switches don't have to be on 3 different VLANs, you can mix them as you choose; just one VLAN extension as a "leaf" off a port based VLAN connected to one of your 3750s.)


Richard Burts Wed, 03/26/2008 - 04:47
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Mahendra


If the switch is unmanaged I do not see how you could configure any VLAN information in it. Therefore each unmanaged switch could be in only a single VLAN. And if it is unmanaged I do not see how you could configure any interface as a trunk, so the switch would connect on an access port to your 3750 switch. Each unmanaged switch could be in a different VLAN if you wanted but I do not see how you could get more than 1 VLAN per each unmanaged switch.


HTH


Rick

evsrajatgupta Wed, 03/26/2008 - 05:42
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Well mahendra,

I think you have all the Vlan on the unmanaged switch. But few thing need to be done manually like IP address.

Example

If we have 3 Vlan and their IP rang are like 192.168.1.0/24 to 172.169.3.0/24.

Here we need 3 connection between manage and unmanaged switches (one for each Vlan).There will be on trunking command in the ports of managed switch, its will simple access ports of their respective Vlan.


On the PC connected to the unmanaged switch, manually configure the IP address with respect to the vlan you want it to work on. Like if you want the PC 1 to be in vlan 1 give the IP address of range 192.168.1.2-254/24 with the default gateway of vlan 1. For the PC in vlan 2 manually configure the IP address of range 192.168.2.1-254/24 and so on.


Remember DHCP will not work properly on the unmanaged switches in the above setup. But it will work fine in one vlan per unmanaged switch.


Please do rate me if the solution works

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