is flapping between port

[duhaas]

I have a particular Vsphere host that several vms that are spewing the following message from my cisco 4507 switch:

Feb 11 14:43:00.768 cdt: %C4K_EBM-4-HOSTFLAPPING: Host 00:50:56:AE:33:4D in vlan 8 is flapping between port Gi5/3 and port Gi5/4

Feb 11 14:43:08.908 cdt: %C4K_EBM-4-HOSTFLAPPING: Host 00:50:56:AE:30:D1 in vlan 8 is flapping between port Gi5/4 and port Gi5/3

Feb 11 14:43:14.696 cdt: %C4K_EBM-4-HOSTFLAPPING: Host 00:50:56:AE:6F:A0 in vlan 8 is flapping between port Gi5/3 and port Gi5/4

These three mac addresses are on one particular ESX host. The vsphere host is a blade, its networking comes from a HP Virtual Connect Switch, the two ports providing uplink are configured on the cisco 4507 as follows:

description ESX Trunk

switchport trunk encapsulation dot1q

switchport mode trunk

spanning-tree portfast

On the vsphere host, I have the following config for my server network:

Any suggestion on what might be causing the error on the switch I would greatly appreciate

[Josh26 · Accepted solution]

Hi,

This is not an "error". The adapter teaming you have configured operates by load balancing in this way.

You could look at setting up a port channel on your switch to implement teaming differently.

[duhaas]

is there a best practice or recommendation as to what the best route to go is? thanks for your help

[jpdicicco]

You have a couple of options:

1) You can setup etherchannels for each of your ESX systems, for each collection of pNICs/vmnics on a vSwitch.

This option tells the switch that all of the ports in the etherchannel can support traffic for the same MACs. It isn't true load balancing, but it may be closer than option 2. This "load balancing" option hashes each pair of IP Src/Dst on a per-packet basis and chooses the same active vmnic for that traffic so long as it is up.

2) You can use PortID or MAC Hash for load balancing.

This option tells your vSwitch to assign each VM port or MAC address to a single vmnic from the "active" group of vmnics. If the assigned vmnic fails, then it will assign the port/MAC to another from the active pool.

I recommend this document for anyone using Cisco networking with VMware.

Happy virtualizing!

JP

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