How to expand dhcp range using ip helper address on 3430

[ovation766]

I have one working dhcp scope on a windows server, and have added another scope, different subnet, to try to resolve dwindling ip addresses.

I have two netvanta 3430 routers, and one vlan, 192.168.1.254.  I've added a secondary ip representing the new scope onto the 3430.  It's

"connected".  I've created a superscope on the windows server, and it's handing out new addresses from the new scope.  Those addresses

are not working however and I understand that a udp ip helper address might solve the problem.  I tried setting up the helper address on the

netvanta, using bootps and domain ports.  I'm sure that i'm clear on whether I need another vlan, or if i'm using the correct ip's to make this

work successfully. thanks in advance for any ideas.

[Anonymous]

- Thanks for posting your question on the forum!

If possible, can you post your configuration to the thread? Please remember to remove any information that may be sensitive to your network.

I believe you are on the right track with setting up UDP forwarding for the second scope. However, it would be helpful to review your configuration before offering any suggestions on what may be going wrong.

Please do not hesitate to let us know if you have any further questions.

Thanks,

Noor

[ovation766]

Hello Noor - thanks for the reply.  In response to your question, it's a flat network using a T1 running between 2 3430 adtran routers, a bunch of windows servers connecting to one router,  printers, wkstns connected to other router.with a  windows dc running active directory and acting as the only dhcp server.   

The second scope is  in the C range with a /24 mask, as was the first scope.  192.168.1.0  and 192.168.2.0, which

would expand the number of addresses to roughly 510.  This is temporary fix, because we don't want 1 large

broadcast domain.  From what I understand, the superscope really just pools all the addresses together,  and hands them out in order, first scope, second scope etc.  It apparently doesn't resolve the issue of addresses in a different

subnet being able to communicate with the rest of the network, hence the ip helper address requirement.   My question i guess is whether this will actually work with a single lan card in the dc, and secondary ip addresses both on the router and on the dc, and one vlan.  And second question is whether it's even worth messing with all this when I could delete the scopes and just expand the mask to /23 on the dhcp server.

[Anonymous]

- Are the two 3430s bridged together or are they routing across the T1? If possible, could you post the configs of your 3430? (Remember to remove any information that may be sensitive to your network).The easiest option may be to just increase your subnet mask, but I would like to look at your current config before making a suggestion. I'm not sure the ip helper command will be helpful if you are bridging, but could be if you are routing. 

Thanks,

Noor

[Anonymous]

- Do you have any further questions on this topic?  If you do, please do not hesitate to reply.

Thanks,

Noor

[ovation766 · Accepted solution]

Thanks for your help with this Noor. I did put into place a flat network

with an expanded, i.e., 254 mask. I did this after realizing that the

windows superscope needs more than

just a grouping together of multiple networks, it requires the helper ip,

which complicates

matters quite a bit, at least it did in my situation. Yes, it's closed at

this point.

Thanks again,

John

On Tue, Apr 2, 2013 at 1:09 PM, noor

[Anonymous]

I went ahead and flagged the "Correct Answer" on this post to make it more visible and help other members of the community find solutions more easily. If you don't feel like the answer I marked was correct, feel free to come back to this post to unmark it and select another in its place with the applicable buttons.  If you still need assistance, we would be more than happy to continue working with you on this - just let us know in a reply.

Thanks,

Noor