MOD5282 DHCP ...

[Mark]

Some more information but no know solution/cause yet.

It seems that when I load up the MOD5282 with new source and try to get a DHCP address, either our Actiontec router will not make issue, or the MOD5282 will not accept. If I reset the router, then reboot the MOD5282 (NOT download), the DHCP functions as expected. I can even switch between static and DHCP and everything works fine.

Any hints/ideas?

[thomastaranowski]

I took a quick look at the sniffer log. It looked like the router was
spacing out (technical term) for several seconds, then responded when
the third dhcp request was made. That's alright, but the response
used one of the earlier transaction IDs. Somehow the router got out
of state with regards to which offer it should be responding to, and
didn't bother to respond to the first 2.


I'm not familiar with that router, but it looks like it may be misconfigured somehow.

[Mark]

thomastaranowski - thank you for your reply. I am in full agreement that our router is the culprit here. It seems as if when I change (flash) the source in the MOD5282 I get this condition, no matter what application I am flashing (i.e. it happens with the ConfigIP demo also).

I looked in my router and did not see anything that I could make sense of, with the exception of a WAN setting. However, WAN settings should control the outside of the router, not the inside. I am going to try to put this system on a seperate LinkSys router and see if I have the same issues.

Another thought that I had was if the MOD5282, when being flashed with new bits, was improperly terminating the DHCP session and causing the router to think that it was still attached. Upon reboot of the MOD5282, the router could be thinking that the previous session is still active and either not responding properly, or with stale data. Just a thought.

[rnixon]

Good job Thomas, you know your stuff.

Some more information but no know solution/cause yet.
It seems that when I load up the MOD5282 with new source and try to get a DHCP address, either our Actiontec router will not make issue, or the MOD5282 will not accept. If I reset the router, then reboot the MOD5282 (NOT download), the DHCP functions as expected. I can even switch between static and DHCP and everything works fine.
Any hints/ideas?

It should not matter how many times a client reboots or requests a lease. The dhcp server keeps a table that includes the device's mac address and assigned ip address. It should keep providing the same ip address for a specific mac address if at all possible. I would expect that repeated requests before the lease termination would probably just add the extra time to the lease. I tried resetting and download/reboot cycles 10 times in a row and did not have a problem with my linksys router.

[Brian Click]

You might check to see if the router expects a FQDN (fully qualified domain name) as well as the DNS name (pDhcpOfferName).

Perhaps the router code has a "feature" that permits a node to acquire an address ONCE on DHCP Discover without a FQDN but subsequent DHCP messages are denied / ignored ("spaces out") unless the DHCP Request includes a FQDN?? Yeah it's a stretch...but a possibility.

The NB DHCP functions don't provide for FQDNs so I outlined how to add that right here --> http://forum.embeddedethernet.com/viewt ... p=495#p495

[rnixon]

Hey Brian, thanks for the link.