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Beginner

Host flapping between ports

Dear All,

Two days back my entire network was behaving in unusual ways.

When is connect to core switc(4506e) through console, i found following -

00:06:51: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2

00:06:52: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2

00:06:54: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2

00:06:56: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2

00:06:58: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3

00:07:00: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3

00:07:02: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2

00:07:04: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3

00:07:06: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2

00:07:08: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2

00:07:10: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3

00:07:12: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3

00:07:14: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2

00:07:17: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3

00:07:18: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3

00:07:20: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2

00:07:22: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3

00:07:24: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2

00:07:27: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3

00:07:28: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2

00:07:30: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2

00:07:32: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2

00:07:34: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3

00:07:36: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3

00:07:38: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3

00:07:41: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3

00:07:42: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2

00:07:44: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2 00:06:51: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2
00:06:52: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2
00:06:54: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2
00:06:56: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2
00:06:58: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3
00:07:00: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3
00:07:02: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2
00:07:04: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3
00:07:06: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2
00:07:08: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2
00:07:10: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3
00:07:12: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3
00:07:14: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2
00:07:17: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3
00:07:18: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3
00:07:20: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2
00:07:22: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3
00:07:24: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2
00:07:27: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3
00:07:28: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2
00:07:30: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2
00:07:32: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2
00:07:34: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3
00:07:36: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3
00:07:38: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3
00:07:41: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/2 and port Gi4/3
00:07:42: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2
00:07:44: %C4K_EBM-4-HOSTFLAPPING: Host 02:26:9E:DA:E9:C3 in vlan 1000 is flapping between port Gi4/3 and port Gi4/2

Please advise. Also when i try to find mac ID 02:26:9E:DA:E9:C3, i couldn't find it in mac address finder

Everyone's tags (4)
14 REPLIES 14
Hall of Fame Community Legend

Host flapping between ports

Hmmmm ... That's not a VM, is it?

Beginner

Re: Host flapping between ports

I have the same issue, my machine on the flapping ports is a hyper v with several vm's.  So is then normal behavior?

 

Thank you

Cisco Employee

Host flapping between ports

Try to trace the mac using the command

show mac-adress address 02:26:9E:DA:E9:C3

Where is gi 4/3 and 4/2 connected?

Thanks

Raju

Beginner

Host flapping between ports

vishalpatil86, is either end of the link configured as a port-channel? It sounds like one end is configured as such and the other isn't. This could cause a spanning-tree loop and many other nasty things.

Beginner

Re: Host flapping between ports

This is maybe spanning-tree loop. Check these ports.

Sent from Cisco Technical Support iPad App

Beginner

Re: Host flapping between ports

Hey visal at first go back to the day when it was working fine...........And just trying to rembember if you have done any changes on the network or i mean to say if you have plugged in any new cables on the switch. .....According to your log its not only the problem of one port so......eventually its being changed that means.....you are having loop on the network.......Plz trying to know if STP is working properly or not........And if you have HSRP configured......dont forget the check the status of stand by IP that matters a lot.......Good Luck

Contributor

Host flapping between ports

I am curious why doesnt that MAC address appear on OUI finder?

http://www.wireshark.org/tools/oui-lookup.html

Beginner

Host flapping between ports

Actually plz try to find out....if you have 2 devices with the same MAC address...........Sometimes.....low end devices are having same mac due to which eventually ..........from port gig 4/3 and 4/2 they are trying to access the network so there if flapping...occuring........

Better you trace each port....... with sh cdp neighbour ..........

If possible remove one cable from either 4/3 or 4/2 and check if the problem exist...........

About the mac address will you plz check out in the neighbour device????

Beginner

Host flapping between ports

I got it you can  try find only 00-1C-23

Is it Dell

Host flapping between ports

Also check the SFP & Fiber port & Physical cbale.

We have faced the similar issue & found SFP & Fiber patch cord faulty

Engager

Re: Host flapping between ports

The first Byte of the MAC address ("02") tells you that the U/L-Bit is set to "local", that means it's not the Burned-In Address of the NIC but locally administered (http://en.wikipedia.org/wiki/File:MAC-48_Address.svg).

Most probably it's a virtual or shared address of a NIC-Team or something like that.

What devices are connected to Gi4/2 adn Gi4/3?

What about an ARP-Entry for 02:26:9E:DA:E9:C3?

How many and what kind of devices do you have inVLAN 1000?

HTH

Rolf

Contributor

Re: Host flapping between ports

Thank you fischer.rolf. and Mike.

I thought I might help by saying what make/model the device was, I have never seen a full MAC not listed in the OUI finder.  But as was suggested, I took off the last 3 octets, and got it.  I wonder if milkmen learned stuff every day like we do

Beginner

I have also this message

I have also this message sunddenly on switch :

a58.d4fc in vlan 810 is flapping between port Gi1/0/1 and port Gi1/0/8
02:34:23: %SW_MATM-4-MACFLAP_NOTIF: Host 0023.ea5a.fcfc in vlan 810 is flapping between port Gi1/0/8 and port Gi2/0/1.

.

...

..

Beginner

Re: Host flapping between ports

Make sure you have vlan 1000 created on the switch, I just experienced this and fixed it by creating the vlan I missed.

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