Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
New Member

Port Flapping - (Redundant Server ports)

We are trying to setup 2 Nokia FWs in a High Availibility setup. Active/standby is are setup. When the active fails we are hoping for a stateful failover to the standby FW. Instead we are getting the following messages on the switch.

2006 Nov 26 11:44:36 %SYS-4-P2_WARN: 1/Host 00:00:5e:00:01:65 is flapping betwee

n port 5/36 and port 5/37.

Do I need to do anything to the port configuration to get this to work?

5 REPLIES

Re: Port Flapping - (Redundant Server ports)

This message indicates that your Catalyst 4000 switch has learned a MAC address 00:00:5e:00:01:65 that already exists in its CAM table on a port other than the original one, which means that this host is dually attached to the switch.

What you can to track down how this MAC address was learned from both ports.

Step 1: Consider port the first port. Issue the show cam dynamic [port] command. If you see the MAC address 00:00:5e:00:01:65 coming

out in the list of the MAC addresses learned on this port, try to see if this is a single host that is connected or if there are multiple hosts registered on that port.

Step 2: If it is a single host that is connected, check the other port that is registered and see if the host is dually attached to the switch. If however, the host has connections to other devices that can eventually lead back into this switch, try to track down the intermediate devices that are in between.

The best way to achieve this (assuming that they are Cisco devices) is to use the

output of the command show cdp neighbors detail.

New Member

Re: Port Flapping - (Redundant Server ports)

I have 2 hosts plugged into the same switch. They have there own MAC addresses and use a virtual MAC to provide failover.

What I have in the DYN CAM on the switch is one port with real MAC and one port with both its real and the virtual MAC.

The virtual moves to the other port when the primary fails. If the failure does not take down the primary link I end up with the MAC on both ports. I get the port flapping errors when this happens.

New Member

Re: Port Flapping - (Redundant Server ports)

Hello Mike,

what kind of switch is it ?

I've got the same problem on 3750 but not on 3550.

Best regards.

New Member

Re: Port Flapping - (Redundant Server ports)

We are using a 4006 but have resolved the issue. We had vrrp configuration issues on the Nokia's.

New Member

Re: Port Flapping - (Redundant Server ports)

Thank you !

788
Views
0
Helpful
5
Replies
CreatePlease to create content