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Cisco 2951 disable adress spoofing

Hi

I have the following problem: On a Cisco 2951, IOS 15.1(3)T, if I manually configure on a host behind my lan interface an ip address for a different network, I get an ip address conflict message and the mac address that conflicts with my computer belongs to the cisco router.

This is my network: Cisco2951 Lan (Gi0/1) – 192.168.61.1/24 – unmanaged switch – Windows 7 PC (192.168.61.10/24 manually assigned)

If I try to configure let’s say 192.168.200.100/24 I get an ip address conflict message as I said before. I think this is a cisco security feature but I can’t find anything about it. The temporary solution I am using now is to configure a secondary ip address on the lan interface.

This is the show run all for my lan interface:

interface GigabitEthernet0/1

ip address 192.168.200.10 255.255.255.0 secondary

ip address 192.168.61.1 255.255.255.0

ip redirects

ip proxy-arp

ip load-sharing per-destination

ip cef accounting non-recursive internal

ip route-cache cef

ip split-horizon

load-interval 300

duplex auto

speed auto

media-type rj45

dot1q tunneling ethertype 0x8100

snmp trap link-status

max-reserved-bandwidth 75

hold-queue 75 in

hold-queue 0 out

no bgp-policy accounting input

no bgp-policy accounting output

no bgp-policy accounting input source

no bgp-policy accounting output source

no bgp-policy source ip-prec-map

no bgp-policy source ip-qos-map

no bgp-policy destination ip-prec-map

no bgp-policy destination ip-qos-map

How can I disable this feature?

If you need aditional info please let me know.

Thank you

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