Question regarding VLAN setup on AP 1142N

[colombo01]

Forgive me if this is newbie type question, my VLAN experience is a little limited.  I have a 1142N AP I want to setup with two SSID's, one for internal clients and one "external" guest clients using two separate VLAN's one for the internal & one for the external SSID.  I know I need a managed switch, but I guess the question I have is will the DHCP server on the "internal" VLAN work to assign an IP address for the "external" VLAN clients.  Additionally, if the DHCP server on the "internal" VLAN will assign an IP address to the "external" clients will there be any issues if my router is an unmanaged router....or does that not matter?

Thanks
Josh

[Rasika Nayanajith]

Hi Josh,

will the DHCP server on the "internal" VLAN work to assign an IP address for the "external" VLAN clients. 

Yes, single DHCP server can assign IP for both vlan/SSID clients

Refer this thread, as I have given sample configuration for multiple SSID with multiple vlan.

https://supportforums.cisco.com/discussion/12353756/best-practice-configuring-2602i-aironet-50-70-users

will there be any issues if my router is an unmanaged router....or does that not matter?

You require managed switch to connect this AP & pass two different vlan traffic to AP. If your router is the L3 gateway for these vlan, then it should support 802.1q vlan tagging.

HTH

Rasika

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[colombo01]

Rasika,

Thanks for the reply.  I need to re-read your post and let things sink in a little bit more.  I'll look over it again and post tomorrow.

For some additional details, I confirmed my router does support 802.1q vlan tagging, so I should be ok there.

Currently, my network DHCP server is a software based DHCP server.  In reading over your post if I understood correctly it sounds like the managed switch would have its own hardware based DHCP server to assign IP addresses to those clients identified on the "external" VLAN.  Did I understand that correctly or did misread something?

I am configuring this setup for a small business application and will need to purchase a managed switch with 16 or 24 ports.  Do you have any recommendations on a particular managed switch that will handle the VLAN configuration and include POE while keeping costs in mind.

Thanks again
Josh

[Rasika Nayanajith]

Currently, my network DHCP server is a software based DHCP server.  In reading over your post if I understood correctly it sounds like the managed switch would have its own hardware based DHCP server to assign IP addresses to those clients identified on the "external" VLAN.  Did I understand that correctly or did misread something?

DHCP server will be software based, even though you defined it on your switch, it is DHCP service running on its OS.

I am configuring this setup for a small business application and will need to purchase a managed switch with 16 or 24 ports.  Do you have any recommendations on a particular managed switch that will handle the VLAN configuration and include POE while keeping costs in mind.

In this forum, most of us discussed about Cisco enterprise grade wireless. Here is 2960X series switch detail, if you are interested

http://www.cisco.com/c/en/us/products/switches/catalyst-2960-x-series-switches/index.html

You may need to check the pricing with your Cisco account manager or from a Cisco partner.

HTH

Rasika

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[colombo01]

Hi Rasika,

I've had a chance to re-read your thread and there certainly is a lot of good information there.  I understand the basic concept, but it'll probably take a bit of trial and error for me to get the configuration correct once I have the equipment.

I would like to confirm that my existing network DHCP server will assign an IP address to both VLAN's, I'm still a little fuzzy how this will work, but I'm guessing it is how the managed switch is configured.  Also, I saw that you mentioned it was good practice to assign wireless users to a different subnet.  Would I want to have a different subnet for my "internal" and "external" wireless network if they're going to be on different VLAN's?  

Something else I'm a bit confused on is; assuming I setup my existing network DHCP server with a different subnet scope for the wireless users and the managed switch connects the two subnets how does the DHCP server differentiate which scope to use when assigning an IP address?

I've attached very simple diagrams of my current and proposed network topology to make sure I'm not being confusing.  A picture is worth a thousand words.

Thanks for your help and time!
Josh

[Rasika Nayanajith · Accepted solution]

Something else I'm a bit confused on is; assuming I setup my existing network DHCP server with a different subnet scope for the wireless users and the managed switch connects the two subnets how does the DHCP server differentiate which scope to use when assigning an IP address?

Let's say you create two SSIDs with vlan 10 & 20 mapping to that. In this case your managed switch or router should have gateway for these two vlan. When wireless client connect to one of them there DHCP Discover messages go as broadcast & reach the switch interface related to the vlan map to that SSID. Then switch forward that broadcast to your DHCP server (if DHCP server is on different vlan that to wireless users) using source as vlan interface related to that SSID.

In this way, two different SSID clients DHCP information go from two different subnet IP, so DHCP server know which subnet IP to lease.

Thanks for the diagram & that explain well what you trying to do. Let us know when you get the hardware so we can assist with configuration required.

HTH

Rasika

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[colombo01]

Rasika,

Thanks for the explanation, that makes sense now!  I appreciate all the help and yeah I'll create a new thread when I get the hardware to work out the configuration.

Thanks again.
Josh