Duplicate IP addresses caused by routers?

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Jun 3rd, 2009
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I'm having an odd issue. I'm running 6509's using Sup 1's running 6.3(3) CatOS with MSFC-1's using IOS ver 12.1(2)E. Yes it's old.

Every now and then Windows XP workstations, both DHCP and statically assigned, detects a duplicate IP. I searched for a rogue DHCP server and there wasn't any. The logs in the MSFC didn't indicate a duplicate IP nor did I see any with test equipment.

The fix, not a solution, was I rebooted my 6509's. Once that was done the issue cleared up.

Does anyone have any theories as to why this might be?

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Giuseppe Larosa Thu, 06/04/2009 - 23:10
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Hello Roland,

but the MSFC1 is acting as DHCP server or as DHCP relay (ip helper-address on the SVI)?

In first case we can guess that reload cleaned the DHCP binding table.

if the MSFC1 is only acting as DHCP relay towards an external server I don't see any possible benefit from the reload.

If the Win XP after patching them had changed something again the reload should not fix an incompatibility

Hope to help



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