03-30-2009 12:15 AM - edited 03-04-2019 04:08 AM
I found that my C4507 switch has received huge of HOSTFLAPPING with the prefix 0C:CC:01 & 0C:CC:01 :
C4507#show log
1378604: Mar 27 18:30:01.959 : %C4K_EBM-4-HOSTFLAPPING: Host 0C:CC:01:00:0C:CC in vlan 10 is flapping between port Gi5/1 and port Gi5/2
1378605: Mar 27 18:30:01.959 : %C4K_EBM-4-HOSTFLAPPING: Host 0C:00:01:00:0C:00 in vlan 10 is flapping between port Gi5/1 and port Gi5/2
1378606: Mar 27 18:30:32.442 : %C4K_EBM-4-HOSTFLAPPING: Host 0C:CC:01:00:0C:CC in vlan 10 is flapping between port Gi5/1 and port Gi5/2
1378607: Mar 27 18:30:32.442 : %C4K_EBM-4-HOSTFLAPPING: Host 0C:00:01:00:0C:00 in vlan 10 is flapping between port Gi5/2 and port Gi5/1
1378608: Mar 27 18:30:41.303 : %C4K_EBM-4-HOSTFLAPPING: Host 0C:CC:01:00:0C:CC in vlan 10 is flapping between port Gi5/2 and port Gi5/1
1378609: Mar 27 18:31:02.830 : %C4K_EBM-4-HOSTFLAPPING: Host 0C:CC:01:00:0C:CC in vlan 10 is flapping between port Gi5/2 and port Gi5/1
1378658: Mar 27 18:40:11.053 : %C4K_EBM-4-HOSTFLAPPING: Host 0C:00:01:00:0C:00 in vlan 10 is flapping between port Gi5/1 and port Gi5/2
Anyone know what is the meaning of these MAC addresses? I can't find the manufacturer for this prefix from web, please help..
03-30-2009 02:55 AM
MAC address prefix 0C-CC-01 doesn't exist. The MAC address most likely belongs to a server with dual nics and not configured properly. You will need to trace this mac address all the way down to the switchport so you can take necessary actions.
03-30-2009 05:15 AM
http://www.bradfordnetworks.com/CampusMgrArchive/1099.html
"We have the same issue every now an again. I can almost guarantee you
that the individual is using a NIC with a Marvel Yukon chipset. For some
reason the NIC advertises this second "rogue" MAC every now and again. "
A simple driver upgrade should fix the problem.
03-30-2009 06:23 PM
Thanks, leolaohoo. I have traced these mac addresses down to switchport, and the 3750-1 & 3750-2 are both connecting to the previous C4507, but I find the following strange result, please take a look:
3750-1#show mac-address-table
Mac Address Table
-------------------------------------------
Vlan Mac Address Type Ports
---- ----------- -------- -----
10 0ccc.0100.0ccc DYNAMIC Gi1/0/8 <= connecting to C4507
10 0c00.0100.0c00 DYNAMIC Gi1/0/8 <= connecting to C4507
3750-2#show mac-address-table
Mac Address Table
-------------------------------------------
Vlan Mac Address Type Ports
---- ----------- -------- -----
10 0ccc.0100.0ccc DYNAMIC Fa1/0/1 <= connecting to Loadbalancer
10 0c00.0100.0c00 DYNAMIC Fa1/0/1 <= connecting to Loadbalancer
It seems the MAC addresses is sourced by the Loadbalancer, but it also showed in 3750-1 which is from C4507. I have checked the span-tree for that vlan, it seems there is no loop and works normal in the vlan...
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