One of the more exciting things I saw at Dell Technologies World this week was the announcement by VMware that they are supporting Microsoft Azure now in additional to AWS. It’s interesting because VMware is trying to provide a proven, stable migration path for companies that are wanting to move to the cloud but still retain their investments in VMware and legacy virtualization. But is offing legacy transition a good idea?

Hold On For One More Day

If I were to mention VLAN 1002-1005 to networking people, they would likely jump up and tell me that I was crazy. Because those VLANs are not valid on any Cisco switches save for the Nexus line. But why? What makes these forbidden? Unless you’re studying for your CCIE you probably just know these are bad and move on.

Turns out, they are a legacy transition mechanism from the IOS-SX days. 1002 and 1004 were designed to bridge FDDI-to-Ethernet, and 1003 and 1005 did the same for Token Ring. As Greg Ferro points out here, this code was tightly bound into IOS-SX and likely couldn’t be removed for fear of breaking the OS. The reservation continued forward in all IOS branches except NX-OS, which pulled them due to lack of support for those protocols.

So, we’ve got a legacy transition mechanism causing problems for users well past the “use by” date. Token Ring was on the way out at IBM in 2001. And yet, for some reason seventeen years later I still have to worry about bridging it? Or how about the rumors that Windows skipped from version 8 to version 10 because legacy code bases assumed Windows 9 meant Windows 95? Something 23 years old forced a major version change?

We keep putting legacy bridges in place all the time to help migrate things. Virtualization isn’t the only culprit here. We’ve found all manner of things that we can do to “trick” systems into working with modern hardware. We even made one idea into a button. But we never really solve the underlying issues. We just keep creating workarounds until we’re forced to move.

The Dream Is Still Alive

As it turns out, it’s expensive to refactor code bases and update legacy software to support new hardware. We’ve hit this problem time and time again with all manner of products. I can remember when Cisco CallManager wouldn’t install on a spare server I had with the same model number as a support machine just because the CPU was exactly 100MHz too fast. It’s frustrating to say the least.

But, we also have to realize that legacy transition mechanisms are not permanent fixes. It’s right there in the name. Transition. We put them in place because it’s cheaper in the short term while we investigate long term methods to make everything work correctly. But it’s still important to find those long term solutions. Maybe it’s a new application. Or a patch to make it work with new hardware. Sometimes, as Apple has done, it’s a warning that old software will stop working soon.

As developers, it’s important to realize that your app may last long past the date you want to stop supporting it. If you could still install Office 2000 on a desktop, I’m almost positive that someone would try it. We still have ways to install and use DOS software! If you want to ensure that your software is being used correctly and that you aren’t issuing patches for it after you’ve retired to a comfortable island with no Internet connection, make sure you find a way to ease transitions and offer new connection options to users.

For those of you that are still stuck in the morass of supporting legacy software or hardware, take a look at what you’re using it for and try to make hard choices where appropriate. If your organization is moving to the cloud, maybe now is the time to cut off your support for an application that’s too old to survive the migration. Or maybe it’s time to retire the Domain Controller That Time Forgot. But you have to do it before you’re forced to virtualize it and support it in perpetuity in AWS or Azure.

Tom’s Take

I’ll be the first to admit that legacy hardware and software are really popular. I worked with a company one time that still had an AS/400 admin on staff because of one application. It just happened to the one that paid people. At Interop ITX this year, the CIO for Detroit mentioned that they had to bring a developer out of retirement to make sure people kept getting paid. But legacy can’t be a part of the future. You either need to find a way to move what you have while you look for something better or you need to cut it off at the knees and find a way to make those functions work somewhere else. Because you don’t want to be the last company running AS/400 payroll over token ring bridged to a Cisco switch on VLAN 1003.