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What data would lead to %IP-4-DUPADDR ?

On my 4500 ,there is syslog information "Mar 31 02:34:26: %IP-4-DUPADDR: Duplicate address on Vlan10, sourced by 000f.202f.b8c0" . is 4500's hsrp ip address.

I don't understand what data packet would lead to %IP-4-DUPADDR ? gratuitous ARP sourced by 000f.202f.b8c0 or any other ?


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Re: What data would lead to %IP-4-DUPADDR ?


Do you mean that 4500 will "see" the arp response for vlan 10 hsrp address sourced by PC "000f.202f.b8c0 "?

For example, 4500----l2 switch----hub---pc1 and pc2.

If pc1 set ip to hsrp address,and pc2 send arp request for hsrp address. Both pc1 and 4500 will response it . Destination mac-address of arp reply by pc1 would not send to 4500 except unicast flooding because CAM table on l2 switch would pointed to port connected to hub.

So how did 4500 know that there is duplicate ip address ?

Re: What data would lead to %IP-4-DUPADDR ?


This message signifies that that has been a duplicate IP address encountered on the network. As being the HSRP IP i.e virtual IP, someone has tried putting the same IP in your network or has got the same DHCP IP. If you have DHCP server in your n/e, you have to exclude this IP from the DHCP pool for Vlan 10. You also might want to check if some user has used this address as static on the system.

Check the PC" 000f.202f.b8c0 " and you will get to the root of this as it is periodically coming up and responding to arps for the vlan 10 hsrp address:

HTH, please rate if it does.

-amit singh

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