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duplicate address


I would appreciate some advise on the following:

1) If 2 PCs have the same IP address on the network, what would be the impact?

2) If a PC is having the same IP address as the gateway, what would be the impact? How do we track on the network if it happens?

3) What would be the impact when I encountered %HSRP-4-DUPADDR: Duplicate address on Vlan502, sourced by 0000.0c07.ac46? I tried to look into the configurations of the network devices but do not find any duplicate HSRP ip addresses, could it be the external WAN link which is using the same HSRP ip address as the router which causes it?

4) Any impact of having same HSRP groups for 2 different VTP domains?

5) For the above, to avoid unauthorised people to access the network, especially those who plug in a switch to disrupt the network, as well as avoid people from using the same ip address as the gateway, other than or in addition to bpdu guard, is it advisable to implement mac address tie to IP address on the DHCP server? If not, any suggestions?




Re: duplicate address

When Hot Standby Router Protocol (HSRP) is running on a device, the %HSRP-4-DUPADDR:Duplicate address [IP_address] on [chars], sourced by [enet] error message can appear on the console if the IP address in an HSRP message received on the specified interface is the same as the IP address of the router receiving the message. The most likely cause of this condition is a network loop or a misconfigured switch that is causing the router to see its own HSRP hello messages.

Check the configurations on all the HSRP routers to ensure that the interface IP addresses are unique. Check that no Layer-2 loops exist. If port channels are configured, check that the switch is configured correctly for port channels. Issue the standby use-bia command so that the error message displays the interface MAC address of the sending router, which can be used to determine if the error message is caused by a misconfigured router or a network loop.

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