%HSRP-4-DUPADDR : Duplicate address

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Oct 30th, 2009
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Hi, I have two 6509 switch and I have configured vlans on them having L2 trunk ports. I am getting error like

%HSRP-4-DUPADDR : Duplicate address [IP_address] on [chars], sourced by [enet]

Please suggest what to do and troubleshoot where is the duplicity?

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Reza Sharifi Fri, 10/30/2009 - 19:38
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Check the configurations on all the HSRP routers to ensure that the interface IP addresses are unique. Also check that no Layer-2 loops exist in your network.



Rupesh Kashyap Fri, 10/30/2009 - 20:09
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I am not seeing STP loop in L2 network.

All HSRP vlan IP is unique. Please help as I am gettin the error for vlan---

329628: .Oct 30 18:12:52 PST: %IP-4-DUPADDR: Duplicate address on Van137, sourced by 0017.5a18.034b

viyuan700 Fri, 10/30/2009 - 21:28
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check if u have the problem mentioned below

If static NAT is configured with the same IP on each router, the routers advertise each other with the MAC addresses, and the routers display the %IP-4-DUPADDR: Duplicate address [ip address] on [interface], sourced by [mac-address] error message. Refer to NAT-Static Mapping Support with HSRP for High Availability for more information.

see the link for more info


Rupesh Kashyap Fri, 10/30/2009 - 23:14
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No NAT is configured, no loop in STP l2 domain, no duplicate IP. Is it possible, if we have same vlan IP on any other L3 domain in our datacenter & we are getting the alert. I mean, Can HSRP cross L3 boundary ?

Peter Paluch Sat, 10/31/2009 - 02:02
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Hi Rupesh,

Double check the HSRP configuration on both your switches once again. Often a small but significant issue is overlooked:

The "standby" command accepts a group number as the next parameter, for example,

standby 1 ip

Here, the standby group number will be 1. However, the group number may be omitted, resulting in a command

standby ip

In this case, the group number is 0.

Now, if two routers are configured for HSRP, one having the group number specified and the other not, actually two distinct standby groups are created inadvertently that indeed collide in their IP address. The solution here is simple: to make sure that the group number is the same, preferably by having it specified explicitly on all routers.

Best regards,


Giuseppe Larosa Sat, 10/31/2009 - 04:01
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Hello Rupesh,

find device with MAC address 0017.5a18.034b

it is sourcing ip packets with

MAC SA = 0017.5a18.034b


the MAC OUI is Cisco so it is another device that is using that is probably an IP address used in SVI vlan137 on complaining node.

I don't see HSRP related issue in this message.

my guess two devices have the same ip address in this vlan (may be the two HSRP members)

Hope to help



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