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New Member

DHCP pool by location

I have a 5800 WLC and 1142 LAP's, I currently use H-REAP to us the local interent connections at each of my 19 locations and use the DHCP server on the firewall's at these locations for client addresses. I would like to have the controller do DHCP for each site versus the local firewall. Each site would have a different subnet as well.

Is this possible? If so, how do I accomplish this? Also, if this is possible, what happens if the WAN goes down? Do the AP's have the ability to do the DHCP locally?

1 ACCEPTED SOLUTION

Accepted Solutions
Cisco Employee

DHCP pool by location

Andrew,

If you want WLC to act as DHCP server you have to

-Trunk those vlans from remote site to Central side where WLC resides. [ essentially you are moving from h-reap to local mode APs ]

-If WAN goes down, your APs are down since now they are in local mode..

-WLC is not a full fledge DHCP server . It can hand only for those clients where dynamic Interfaces/management interface are configured.

-APs do not have ability to act as DHCP server.

What you have with Local switching and Firewall acting as DHCP server is optimum solution.. If you have any other valid reasons let us know...

Here are good docs on H-reap and WLC acting as DHCP server :

H-reap :

http://cisco.com/en/US/tech/tk722/tk809/technologies_tech_note09186a008081103d.shtml

http://www.cisco.com/en/US/products/ps10315/products_tech_note09186a0080736123.shtml

http://www.cisco.com/en/US/products/ps6366/products_tech_note09186a0080b3690b.shtml

http://www.cisco.com/en/US/docs/wireless/controller/7.0MR1/configuration/guide/cg_hreap.html

http://www.cisco.com/en/US/docs/wireless/controller/7.0MR1/configuration/guide/cg_hreap.html

DHCP on WLC :

http://www.cisco.com/en/US/products/ps6366/products_tech_note09186a0080af5d13.shtml

Thanks..Salil

8 REPLIES

DHCP pool by location

If you have the WLC handle DHCP you will break if you lose connection. Aps dont have DHCP pools configured on them the WLC does.

__________________________________________________________________________________________ "Satisfaction does not come from knowing the solution, it comes from knowing why." - Rosalind Franklin ___________________________________________________________
New Member

DHCP pool by location

So, if I decide loosing DHCP as a result of a WAN outage is not a deal breaker then the rest is possible from the WLC? I've found several documents regarding DHCP on the controller, however not specificlly about how I would like it done, having DHCP pools for each subnet or group of APs. Can this be done and is there some documentation or guidliness you could point me to or explain it to me here.

Hall of Fame Super Silver

DHCP pool by location

Andrew,

Just to add to George's post.  Why not use the same dhcp server that your wired users are using.  If your FW is doing that instead of a local dhcp server or centrally located dhcp server, you should just keep using that.  I only would use the WLC as a dhcp server for guest access and that is if my clients don't want to use their FW's as dhcp server.  This is centrally switched also not locally switched.  The WLC isn't going to respond to dhcp broadcast from the wired side, which is what it would be if you locally switch traffic on a wlan and use an ip helper on the vlan interface pointing to the WLC.

Scott

-Scott
*** Please rate helpful posts ***
Cisco Employee

DHCP pool by location

Andrew,

If you want WLC to act as DHCP server you have to

-Trunk those vlans from remote site to Central side where WLC resides. [ essentially you are moving from h-reap to local mode APs ]

-If WAN goes down, your APs are down since now they are in local mode..

-WLC is not a full fledge DHCP server . It can hand only for those clients where dynamic Interfaces/management interface are configured.

-APs do not have ability to act as DHCP server.

What you have with Local switching and Firewall acting as DHCP server is optimum solution.. If you have any other valid reasons let us know...

Here are good docs on H-reap and WLC acting as DHCP server :

H-reap :

http://cisco.com/en/US/tech/tk722/tk809/technologies_tech_note09186a008081103d.shtml

http://www.cisco.com/en/US/products/ps10315/products_tech_note09186a0080736123.shtml

http://www.cisco.com/en/US/products/ps6366/products_tech_note09186a0080b3690b.shtml

http://www.cisco.com/en/US/docs/wireless/controller/7.0MR1/configuration/guide/cg_hreap.html

http://www.cisco.com/en/US/docs/wireless/controller/7.0MR1/configuration/guide/cg_hreap.html

DHCP on WLC :

http://www.cisco.com/en/US/products/ps6366/products_tech_note09186a0080af5d13.shtml

Thanks..Salil

New Member

DHCP pool by location

Thanks everyone for the feedback and information/docs. I agree that the local switching and DHCP being served from the local firewall is the optimal setup and is why I have my current WLAN running that way. However, I was investigating this for my WLAN upgrade to the WLC and LAPs, as my UTM firewalls have issues with DHCP flooding and do not flush well (current firmware), thus the alternative solution being DHCP from the WLC or some other DHCP server.

At this point I think I will deploy in my current setup with DHCP running from the local firewall and see if my WLAN stability and reliability improves, then if DHCP is still an issue, I'll look at alternatives then, like replacing the McAfee UTM SG580s at all remote sites with something newer and better.

Thank you,

Andrew

Hall of Fame Super Silver

Re: DHCP pool by location

Andrew,

Have you thought about using your L3 switch at each site to possibly hand out dhcp to your clients.

Sent from Cisco Technical Support iPhone App

-Scott
*** Please rate helpful posts ***
New Member

Re: DHCP pool by location

Scott,

The switches I have on the public side of the network are L2. I have a router on the staff side that I could run DHCP off of but that would require me to open a hole in the firewall to our private LAN. But, yes I have thought of doing that.

Hall of Fame Super Silver

Re: DHCP pool by location

Okay I understand now.

Sent from my iPhone

-Scott
*** Please rate helpful posts ***
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