DHCP relay IP and gateway IP, possible bad logic?

Alan DeKok aland at deployingradius.com
Fri Mar 1 16:12:38 CET 2013


Igor Smitran wrote:
>  In case when freeradius is talking to a DHCP relay it should *always*
> send answears to a initiating relay IP. But, it doesn't.

  Can you supply the debug output?

> Cisco CMTS is using 10.10.10.1 as his giaddr for all requests made by
> CM's, MTA's and CPE's.
> All replies should go to 10.10.10.1.

  Usually... there is are some weird requirements on how DHCP operates.

> But, currently, if CPE gets public IP 200.200.200.2 with gateway
> 200.200.200.1, freeradius tries to send reply to 200.200.200.1 instead
> of 10.10.10.1.

  The DHCP code ignores the *routing* gateway address.  It instead uses
the DHCP giaddr field to send responses.

  Again, debug output would help here.

  Alan DeKok.


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