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Author Topic: strange feature/bug with dhcp and win7 in an ers5632 / ers 4500 env  (Read 2196 times)

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Offline hosh

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same months ago we had interesseting problem with two ers5632 (IST/SLT configuration, handful of vlans and dhcp-helper), DHCP did not worked on the network, only when the client was directly connected to the switch where the serve was connected.
avaya worked on the dhcp part of the software (not official) of the ers5632 and with a new update dhcp worked just fine.

in the same env we have an interessting feature now with win7. the client get the base os and will shiped to the workplace - started up und get the last pieces of software incl some win7 updates etc. now if the client reboot, he dont get any dhcp information from the server. and to strange up the whole thing a littlebit if you try to give him a static ip, you dont get any connection to the gateway or somewhere else.
i can see the mac of the client in forwarding DB of the connected switch (ers 4500t-pwr 4units sotware now 5.6.3).
Ok hier is the realy strange thing, on the same stack there is a little ers3500 10Port switch connected. Now if we transfer the client to the ers3500 and start him up, everything is fine and dhcp works perfectly, and if we transfer the client back to the workplace it works also great. the client get his ip and ist fully connected.

we updated the stack yesterday because, avaya did some work on the dhcp behavior in the software. but no luck.
i monitored i.e. a client while try to get an IP from the dhcp. the client send his broadcast out and get an offer back from the dhcp-relay (ers5632) with all inforamtion, but the client did not use this information.
if we do the workaround with the ers3500 the dhcp process works fine.

i did some research on the web and found an issue on windows vista - > D-Flag - dhcp behavior change from xp to vista/7 - we tried today to fix this by changing the registry entry, but nothing positiv happend.

i have no idea and i dont think it is prim a ers - problem, may be some has an idea in connection with windows 7

if there is any understandig problem because of my english - sorry for that

so far thx for reading

Offline Michael McNamara

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    • michaelfmcnamara
    • Michael McNamara
Re: strange feature/bug with dhcp and win7 in an ers5632 / ers 4500 env
« Reply #1 on: July 17, 2013, 08:01:46 AM »
I would suspect a potential ARP/FDB issue... especially since you mention the problem isn't resolved with a static IP address.

What's performing the routing? You mention you were able to locate a MAC/FDB entry... what about an ARP entry?

I've also see VLAN configuration issues cause problems with DHCP replies. Make sure that the port belongs to a specific VLAN and that VLAN is set as the DefaultVlanId. If you suspect DHCP, setup a mirror port and run a packet trace to see if there's a DHCP reply being broadcast.

Good Luck!
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