Virtual Connect Ethernet Load Balance Policy for LACP Etherchannel and VMWare 3.5

[Robert_266]

I have two Cisco 3750E switches in stack. A C-7000 enclosure with Bays 1,2,5,6,7,8 with VC-Ethernet modules. I'm using ports 5&6 in Bays 1&2 with LACP etherchannel trunks, (that's one set of trunks per bay). I have VMWare 3.5 on 5 BL460c blade servers. The load balance policy on the 3750e switches is set to src-dst-ip. I have the VMWare servers set to IP hash. Two of the 5 servers are making my vlan flap. If I change the virtual switch lb policy to failover the vlan flapping stops. I found a PDF that states the VC-E modules use src-dst-mac and/or src-dst-ip for load balancing the lacp etherchannels. How can they use both? Does anyone know how to force it to be just src-dst-ip? Why are the other 3 servers not flapping the vlan? (Since there are only two paths, am I just getting lucky src-dst-mac = src-dst-ip?)

Rob

[HEM_2]

Rob, regardless of the load balance policy in VC or Cisco, you shouldn't be seeing flapping. What kind of flapping are you seeing? MAC Address flapping or port-channel flapping? Do you have an example of the console or log message you are seeing?

VC only supports LACP so your channel-groups on the Cat3750's should be channel-group x mode active or mode passive NOT mode on or desirable.

I think the VCE modules use src-dst ip when the traffic is IP traffic. When it is NOT IP traffic, then the src-dst MAC is used.

[Robert_266]

Yes, the channel groups are set to mode active. You are correct, if the traffic contains an IP header then the VC uses src-dst-ip. Here is a copy of the error message from the console.

840: 6d00h: %SW_MATM-4-MACFLAP_NOTIF: Host 0050.567c.e5fd in vlan 10 is flapping between port Po3 and port Po4.

Rob

[HEM_2]

Robert,

ahh, ok. in VMWare ESX, you can only use IP Hash when all the VMNICs in a Virtual Switch connect to the same physical switch and the physical switch is configured for etherchannel or static 802.3ad. This is impossible in VC because each blade NIC connects to a different VC module on the midplane.

You can use load balancing, you just need to change the hashing algorithm to any other mode.

[Lee Carey]

Hi having a similar issue. Was this resolved by chaging the load balancing algorithm?

Thanks