Cisco 4507 hostflapping log entries

[bburke]

We have a vSwitch with 6 physical NICs setup in the same port group on our ESX 3.0.1 server. We have each of those physical NICs plugged into the same blade on our Cisco 4507. We currently have 2 vm's running on the server and have noticed that when we issue a "sho logging history" command on the cisco, the following entries have started showing up:

entry number 453783 : C4K_EBM-4-HOSTFLAPPING

Host 00:50:56:AC:73:C6 in vlan 760 is flapping between port Gi5/5 and port Gi5/13

timestamp: 825484364

the mac address is the mac of one of the running vm's and also the 4507 ports in the log entries seem to change periodically.

Can someone shed some light on what's happening with the vSwitch and port group to cause this to happen? Also, is it something that is going to degrade the performance of our 4507 or of our vSwitch or both? Is there a particular way that we need to configure the Cisco switch ports to help it deal with this type of activitiy better?

[admin · Accepted solution]

What load balancing algorithm are you using?

This would be normal behavior for ip-based.

If so - turn etherchannel on, on the switch

[bburke]

Right now it is set to "Port ID" on the vSwitch and "Source XOR Destination IP Address" on the cisco...but that is not on purpose...we are relatively new to VMware and Cisco and haven't changed either side's settings yet.

When we set etherchannel up on the cisco, will we need to change either sides algorithm?

[Paul_Lalonde]

It looks like your Cisco is already configured for IP-hash load distribution (Etherchannel).

Set the VMware side to IP-hash load balancing and you should be all set.

Paul

[BenConrad]

Did you create a "admin group" for the Etherchannel on the Cisco? On my 6509 I create an admin group for ports 1..x even if I'm not spanning modules. I've seen that if you don't create a admin group you may get Etherchannel ports in different admin groups.

[bburke]

Thanks for the tip. That appears to have done the trick, as the hostflapping entries have stopped.

One other question:

When viewing the network adapters, from the Configuration tab of the ESX 3.0.1 server, through VirtualCenter 2.0.1, how does the "Networks" column get populated? It is showing an odd array of Network IP ranges for the VLANs on our network and I just can't make sense of the ranges that are being displayed.