VLAN trunking, or tagging, is a powerful feature that allows ESX virtual machines to connect to multiple networks. However, your network team may not want to enable that. In fact, I have come across many situations where trunking is not done to servers, but only to switches for VLAN availability. To break that mold, we have to start with education on the VMware networking technologies.
Most of us are not network admins as well as virtualization admins, so we have to start with some good resources to “get what we want.” Without VLAN trunking, each VLAN you would want to connect to would require its own physical interface. That clearly is a growth and agility inhibitor as well as incredibly expensive for additional cable runs and interfaces on your ESX servers. Quoting Andrew Kutz, “that makes ESX practically worthless.” So I am on a mission to turn the tide. There is a good resource online from VMworld 2006 that explains the ESX networking so that we can inform ourselves, and better integrate with our network staff to ensure all standards are met.
With networking, configuration consistency among ESX servers becomes absolutely critical (as is with other areas of VI3). It is important to deliver the ESX configuration as planned, as if there is a variation and an outage or other networking issue, there may be a swift change of heart from your networking staff.
Readers, I invite you to share your experiences with making the case for trunking below with a comment.