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Duplicate address x.x.x.x on Port-channel10.101, sourced by 0080.7733.b2f

HI,

I am getting the following log message on my L3 device and the L3 switch hangs. I have restricted telnet session on the L3 device. What is causing this ?

32w1d: %AUTOSTATE-6-SHUT_DOWN: Putting interface Port-channel10.131 into Autostate mode

32w1d: %SYS-5-CONFIG_I: Configured from console by vty0 (127.0.0.2)

32w1d: %AUTOSTATE-6-BRING_UP: Taking interface Port-channel10.131 out of Autostate mode

32w1d: %AUTOSTATE-6-SHUT_DOWN: Putting interface Port-channel10.131 into Autostate mode

32w1d: %AUTOSTATE-6-BRING_UP: Taking interface Port-channel10.131 out of Autostate mode

39w3d: %IP-4-DUPADDR: Duplicate address x.x.85.254 on Port-channel10.101, sourced by 0080.7733.b2f9

48w2d: %STANDBY-3-DUPADDR: Duplicate address x.x.83.251 on Port-channel10.102, sourced by 0000.0c07.ac66

I tried to track these two mac addresses 0080.7733.b2f9 and 0000.0c07.ac66

These mac addresses belong to IP phones which are connected to a L2 device which in turn cascaded to the L3 switch.

Whats the meaning of "Duplicate address x.x.85.254 on Port-channel10.101, sourced by 0080.7733.b2f9 "

x.x.85.254 is the L3 IP(Virtual L3 interface) on the L3 switch.

Is the IP phones MAC address conflicting with the mac address of the L3 switch?

How can I find the L3 switch's system mac addresses.

Appreciate some detailed explanation.

4 REPLIES
Anonymous
N/A

Re: Duplicate address x.x.x.x on Port-channel10.101, sourced by

Hi,

Just an idea : look at the STP instance of the concerned VLAN (Virtual L3 interface). it can be caused by a loop.

symptoms ("show proc cpu hist" and "sh spann vlan x detail") and try to look at "Number of topology changes ".

it was just an idea, hope it helps

New Member

Re: Duplicate address x.x.x.x on Port-channel10.101, sourced by

On one of the L2 switch which is connected to L3 device the following log message is displayed.

SPANTREE-2-ROOTGUARD_BLOCK: Root guard blocking port on Fa0/44 on VLAN102

New Member

Re: Duplicate address x.x.x.x on Port-channel10.101, sourced by

These messages are often caused by a spanning tree loop in the network. It could well be that the phones are causing a loop, what happens if you disconnect them?

Re: Duplicate address x.x.x.x on Port-channel10.101, sourced by

Can you double check the MAC addresses.. 0000.0c07.ac66 is a virtual MAC address generated by HSRP. This would be for group #102 (66Hex).

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