Why VMware Load Based Teaming (LBT)

VMware load based Teaming (LBT) is one of the great feature that was introduced a while back with vSphere 4.1, though it seems many admins have over looked it. As part of my job in consulting, I get to see many customers environments through out the year. It is really common to see customers who never get their hands or heads around LBT. What surprise me the most that many of these are in a desperate need for a similar feature. Many of them already have the Enterprise Plus license which include LBT in it, & its just a matter of enabling to start benefiting of it. For these reasons, I have decided to share why the Load Based Teaming feature offered within our Distributed switches is a great feature and can be of a great use to many of you out there.

The easiest way to see how beneficial LBT can be is to look at the problem it solve. Imagine you are using a virtual switch with the default setting of “Route based on the originating Virtual Port ID” or “Route based on MAC addresses” for the teaming load balancing policy. The way¬† “Route based on the originating Virtual Port ID” & “Route based on MAC addresses” distribute VMs network load across your uplinks by distributing the number of VMs evenly across all the vNICs involved in the team. While this cut it well in normal scenarios, there is scenarios where this can cause a problem. Let’s take a look at the image below.

Looking at the above image, you can understand that load balancing policy such “Route based on the originating Virtual Port ID ” & “Route based on MAC addresses” can end up with more heavy load on one of your vNICs rather than the other vNICs as the mapping between the VM & the vNIC is fixed and does not consider the load the NIC has it just consider how many vm each vNIC has and it make sure that they are distributed evenly across vNICs though without taking into consideration the amount of load each vm is generating. As you can tell few vms in your environment can make up the majority of network traffic load in your environment and if these all landed randomly on the same vNIC that vNIC can be over loaded and your vms will perform poorly although you have other vNICs that almost idle. VMware has introduced LBT to resolve this problem in particular. VMware Load Based Teaming (LBT) is aware of how much traffic is pushed toward each vNIC and will balance the VMs accordingly in case of contention in any vNIC which help reduce the chance of over loading a single vNIC while others are idle. As you can see LBT resolve a very valid case, & you should really consider using it if you own the Enterprise Plus edition, & maybe consider upgrading to the ENT+ license if you need such a feature. Its important to mention that Distribute Switch is required in order to have LBT, as LBT is not offered with the standard virtual switches.

Enabling VMware Load Based Teaming (LBT) is an easy task. Below are the steps you need to do:

1- In your distributed switch right click the port group that you want to enable LBT for. (LBT is enabled per port group)

2- Choose Edit settings

3- Choose Teaming and failover

4- for the load balancing setting choose “Route based on physical NIC Load”

5- hit OK accepting the change

You are now ready to enjoy your LBT!. For those of you who love to see instructions in video below is a great video by Erick Sloof that show how to enable LBT as well how it compares to the other policies in the way it perform.

Hope this get to be useful for many of you!

Comments

  1. Nice post, just wondering if LBT is switch agnostic.

  2. Hi O,

    Yes, I confirm LBT is switch agnostic if you are talking about your physical switches. it should work with any standard physical switch you have as its more to do on the host and nic side rather than anything to do with the switch. If you are talking about the virtual switch, then it require a dvswitch.

    Hope this help,
    Eiad

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