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DHCP issues

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10 replies

by mark_lt

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3 subnet 3 NT domains, connected via layer3 routing switch.

DHCP, and all broadcasts seem to be failing for certain systems, even net send fails to go through. Whilst others appear to be fine, any clues ?

Setting client to static IP sorts it out, but thats not the answer

10 replies

by john k winiger

It would seem that your switch is filtering out all broadcast traffic which can be a normal thing. The point to subnetting is to prevent broadcast storms and the like. Anyway to answer your question you need a DHCP relay agent. You should first lookto see if the switch can be configured to either allow or relay the dhcp broadcast and if not just install the relay agent on a machine on each subnet that is not on the same one as the dhcp server. The agent would be best on a server for avaliblityreasons. What kind of switch is it?

by mark_lt

maybe I didnt explain enough, each subnet has its own dhcp server, but some users on the same subnet are not getting broadcasts from their own net.

its an Intel 550 8 port routing switch which provides the main backbone to the network.

by john k winiger

OK, so since each subnet has it's own dhcp server it's safe to say there is no problem with clients getting addresses from the dhcp servers, correct?
When you say "broadcast" can you give exact example? Something like the net send command not working could be other things like not having the messanger service running on the receiving machine.
Can you ping between all machines and does network neighborhood see all machines?
Give me a few exact things you are tring to do and we can go from there..

by mark_lt

It was all working, net send etc, dhcp, no probs at all, everyone can ping everyone, but dhcp and net send has now stopped woking for some users

by curlergirl

Are you seeing any error messages on the DHCP server? Is it issuing a NACK, or are you getting some other sort of DHCP errors in the System log? Or are the workstations not even able to see the server? If it's the latter, then I'd say it's a NIC, switch/hub or cabling issue. . .Hope this helps!

by mark_lt

No naks, no error logs, if ip is set to static then all works fine, its just the getting a dhcp IP and netsend that doesnt. DHCP is running fine for 95% of the users, just a few who are having problems

by deltree

you have probably already verified this, but have you made sure that there are available addresses in each DHCP scope for all subnet workstations?

by mark_lt

yes, DHCP has loads of spare addresses, about 60% spare.

Am sure this is the routing switch that is doing it

by mark_lt

if I set static IP, then go back to dhcp, the client then works, until the next time it has a problem

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