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Community Member

Duplicate MAC Addresses with Sun Equipment on the same VLAN

I am sure someone else has dealt with this before. We just put in a new CAT4003 switch and moved a number of sun 5xxx servers with multiple NIC's over to it. I am now getting an error MSG's about FLAPing and having to relearn Addresses. Seems that SUN's use the same MAC Address for all NIC's installed in a server by default. We have fixed the problem by forcing a different MAC Address on the second sun NIC. However there must be a way to correct this problem in a Switched VLAN environment when both NIC's are part of the same VLAN. Any Ideas. Thanks.

3 REPLIES
Community Member

Re: Duplicate MAC Addresses with Sun Equipment on the same VLAN

Hi,

Yeah , you need to set the local-mac-address to true on the SUN machine and assign a different mac to the e-net cards using the ifconfig command.

Also , if you want this to survive a reboot , please make this changes in the startup files in the SUN machine .

Thanks & Regards,

Srivathsan A

Sr. Customer Service Er.

Wipro Infotech

Community Member

Re: Duplicate MAC Addresses with Sun Equipment on the same VLAN

I do not think it is possible to have same MAC address for two NICs even if they are in the same VLAN in a switched architecture. One solution for the problem that I could think of, is to put both these NICs to a hub and cascade this hub to a switchport on 4003.

This may not be scalable/Practical solution though!

Cisco Employee

Re: Duplicate MAC Addresses with Sun Equipment on the same VLAN

On a catalyst, one MAC address can only be learned on one port in a VLAN. Though, the same MAC address can be learned on different ports without any problems if those ports are part of different VLANs. If the same MAC address is used on several NICs connected to ports in the same VLAN, the MAC address will 'flap' between those ports all the time. The only solutions are either to hardcode different MAC addresses for each NICs or put the ports in different VLANs.

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