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Community Member

connectivity issues after changing the mac address on SVI interface

Hi

after changing the mac address of an SVI on a 2950 switch  the interface became unpingable.

The following note can be found here http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a00801c9b4e.shtml

Note: In Cisco IOS Software Release 12.1(13)EA1 and earlier, the switch allows configuration of the mac-address command in the interface. But this command causes connectivity issues. This command-line interface (CLI) configuration issue has been fixed in Cisco IOS Software Release 12.1(14)EA and later.

But the switch is running the latest IOS to date:  12.1(22)EA13.

the following is the configuration of the SVI

interface Vlan1

ip address 192.168.0.1 255.255.255.0

mac-address aaaa.bbbb.cccc

any help ?

7 REPLIES
Cisco Employee

Re: connectivity issues after changing the mac address on SVI in

Hello,

After changing the MAC address on the interface, have you cleared the ARP

cache on the PC/Switch? Can you check the PC's ARP cache to make sure that

you have the correct MAC entry for the switch IP?

Regards,

NT

Community Member

Re: connectivity issues after changing the mac address on SVI in

Hi NT

Yes I have cleared the ARP cash. The PC is getting the new MAC address in response to the ARP request, but the ping fails.

regards

HH

Cisco Employee

Re: connectivity issues after changing the mac address on SVI in

Hello HH,

It seems like the image 12.2(22)EA13 does have the issue with MAC address

change. The switch exhibited the same behavior in one of my lab setup.

Unfortunately, even it if it is a bug, there is not much anybody could do

about it as 2950 is end-of-life product and there are no new software

development/patches for that hardware.

Regards,

NT

Community Member

Re: connectivity issues after changing the mac address on SVI in

Hello NT

thank you for your cooperation.

unfortunately you have confirmed my doubts.

this is most inconvenient because I have 2 switches on my LAN with the SAME BIA (000d.286e.0b40)

and if i cannot change the mac addresse of one of them, i'm not gonna be able to manage them remotely.

any idea for a workaround for this issue ????

Regards

HH

Cisco Employee

Re: connectivity issues after changing the mac address on SVI in

Hello,

Please remove the following line from the configuration:

nat (inside) 1 192.168.100.0 255.255.255.0

Also, what is the IP of the DNS server you are using? Could you use 4.2.2.2

as your DNS server and see if that helps?

Regards,

NT

VIP Super Bronze

Re: connectivity issues after changing the mac address on SVI in

Hi,

The note you provided from this document is for 3500 series switches.  You are using 2900 series and under the same section it says:

The Catalyst 2900XL/3500XL switches recognize the mac-addresscommand but do not accept or support the command. This output is from a Catalyst 3500XL with Cisco IOS Software Release 12.0(5)WC3b:

HTH

Reza

Community Member

Re: connectivity issues after changing the mac address on SVI in

Hi Reza,

the note you gave concerns the 2900XL/3500XL.

I am using a  C2950G-24-EI , which is concerned

according to the document, the note i gave "pertains to the Catalyst L2 fixed configuration switches 2940, 2950/2955 and 2970 (VLAN interface) as well as the Catalyst L3 fixed configuration switches 3550, 3560 and 3750 (VLAN and L3 interface)"

Regards

HH

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