MAC Address table entries.

[ryannash0011]

Hello,

Quick question regarding mac address tables.

I have one switch acting as basically a dumb switch. Its a 3750 x running IOS 15.3.

A server has indicated there is an IP address conflict in the network. From what I can tell the only thing that can be causing this is a whole bunch of new work stations operating of the switch running windows under a single VLAN.

I am not 100% but I have a feeling windows may be causing this as I think when these work stations are connected to a port they send an arp "request" for the most part... meanwhile the switch will be doing the same thing via DHCP except it'll be trying to assign that work station an IP address.... Will this cause the following error on the server????

Duplicate IP Address 0.0.0.0

I have looked at the cisco work around at the following link....

http://www.cisco.com/c/en/us/support/docs/ios-nx-os-software/8021x/116529-problemsolution-product-00.html

I have the probe delay 10 command set on the switch but still I get the same error on the server... When I do a show mac address-table I see roughly 85 mac address in a switch that has 4-5 workstation hanging off it, this does not make sense to me how could I have 85 mac addresses on a workgroup switch.... Further to this ALL these mac address are linked to the same port on my workstation VLAN.

Is this as simple as it sounds or am I missing something, I am not a computer genius and have guys who sit next to me for that who are ADAMENT their computers are not affecting this switch and further to that the network and servers.

Apologies if this has been answered before. Any advice would be greatly appreciated... And yes if this is a stupid question feel free to send the hate.

Cheers.

[InayathUlla Sharieff]

Check this:-

http://www.cisco.com/c/en/us/support/docs/ios-nx-os-software/8021x/116529-problemsolution-product-00.html

HTH

[ryannash0011]

Hey,

Thanks for that. I posted that link in my post but I still dont fully understand how it all works. Really new in the industry.

Thanks for your help.

Cheers.

[Carlos Villagran]

Hi!

If you have a switch connected to another switch it is normal to see many other MAC addresses other that the ones of hosts directly connected to the access ports. 

Can you confirm your switch is connected to other switch?

Regards!

JC

[ryannash0011]

Yep it is connected to another switch. This switch also has the probe delay command in its config.

So its fair to say that the 80 odd mac addresses could be related to the switch we connect to? That makes sense. Thanks for that.

If when I do a sh mac address command on  our work group switch it shows the mac addresses causing the error are directly related to our work group vlan.. Meaning the only devices connected to any port configured for that vlan port are laptops.

Does not really solve anything but thought I should mention it also.

Really appreciate the reply,

thank you.