[[!toc]]
-## What is this "renumbering" all about?
-
-As you may have heard, MIT has recently sold half of its IPv4 address space
-to Amazon in order to fund various network infrastructure upgrade projects.
-While there are enough remaining addresses for everyone and everything that
-was using one before, some rearrangement is required to make sure that
-everyone's IP addresses are in the smaller space that will be left after
-Amazon takes over the space that they have purchased. That takeover will
-happen later in June.
-
-All of the IP addresses used by VMs on XVM since its inception were,
-unfortunately, in the part of MIT's IP address space that has been sold to
-Amazon, and thus all of our IP addresses need to change. You can read the
-official explanation of this sale and MIT's upcoming network upgrades
-[here](https://ist.mit.edu/network/next-gen-mitnet-faq), but be sure to
-continue reading this FAQ, because IS&T's description of how the academic
-buildings and residence halls are being migrated does not apply to XVM.
+## What is this "renumbering" all about? Didn't we already do this last year?
+
+If you were an XVM user one year ago, you may remember having your VM(s)
+renumbered from IP addresses beginning with `18.181` to IP addresses
+beginning with `18.49` back then. We are being required to renumber
+again by IS&T. Please contact IS&T if you have questions about why
+we are being required to renumber. The process this time will be very
+similar, except that this time, addresses will be changing to ones beginning
+with `18.25`.
## Do I need to take any action?
## When will my IP addresses change? Can I postpone this? Can I migrate early?
We plan to begin automated migrations of VMs to their new IP addresses on
-Monday, June 4, 2018. This process is expected to take somewhere between
+Monday, August 5, 2019. This process is expected to take somewhere between
a few days and one week.
There are several forces at play that we do not control, so there is very
-limited flexibility that we can offer. Amazon will take control of the
-space that they have purchased on June 26, 2018. IS&T needs SIPB and XVM to
-vacate our old IP space well before then so that they can carry out various
-preparatory tasks before the official transfer to Amazon.
+limited flexibility that we can offer.
If your VM requires special coordination in order to be migrated, we will
work with you to find a time that works well, possibly earlier than the
## What will my new IP address be? How can I tell if my migration has happened?
-Your old IP address was of the form `18.181.xxx.yyy`. Your new IP address
-will be of the form `18.49.xxx.yyy` where `xxx` and `yyy` will remain the
-same. If your VM's networking is statically configured and you will be
-updating this info manually because you cannot switch to using DHCP, it
-is critical that you note that the gateway and netmask will also be changing.
-Please see the question on what to do if you use static addressing below.
+Your old IP address was of the form `18.49.xxx.yyy`. Your new IP address
+will be of the form `18.25.zzz.yyy` where `yyy` will remain the same and
+`zzz` will be `xxx + 128`. If your VM's networking is statically configured
+and you will be updating this info manually because you cannot switch to
+using DHCP, it is critical that you note that the gateway will
+also be changing. Please see the question on what to do if you use static
+addressing below.
Before your migration, you can see what your new network parameters will
be by visiting XVM's website at <https://xvm.mit.edu/> and clicking the
Once your migration has occurred, the "IP:" line on the info page and
the IP address on the line for your VM on XVM's main webpage will show
-your new address, which begins with `18.49`.
-
-## I rebooted my VM after its IP migration happened, and now I can't reach it on the network. What should I do?
-
-The very first time you restart your VM after its IP migration has occurred,
-it is necessary to do so by completely turning it off and then turning it
-back on. A reboot is not sufficient due to some internal state on the
-XVM infrastructure servers that is not cleared out when a VM reboots without
-being turned completely off. Once the VM has been through one complete
-powercycle, further reboots should work fine. We apologize for the
-inconvenience.
+your new address, which begins with `18.25`.
## My VM's networking is statically configured. What should I do?
info page. On that page, you will be able to see both the current and
new IP address, netmask, and gateway. There will also be a new button
on the page with a message above it saying that you can reconfigure your VM
-with the new IP parameters (make sure you get the netmask and gateway
-correct; they will not be the same as the old ones) and then click the
+with the new IP parameters (make sure you get the gateway
+correct; it will not be the same as the old one) and then click the
button. If your VM is running, clicking the button will powercycle your
VM. If your VM is not running, clicking the button will update XVM's
configuration for your VM and tell you to turn it on to complete the
You should wait for your VM's IP address to be migrated. Once that
happens, you will need to either restart your AFS client, or (perhaps
-more easily in some cases) turn your VM off and then back on (note that
-a reboot will not result in a functioning network connection; the very
-first time that you restart your VM after its IP migration, you must do
-so by completely turning off the VM and then turning it back on). If you
-are curious about the technical reasons for this, see the next paragraph.
-You do not need to contact us about this.
+more easily in some cases) reboot your VM. If you are curious about the
+technical reasons for this, see the next paragraph. You do not need to
+contact us about this.
Restarting the AFS client after you are renumbered is necessary because
after your AFS client starts up, the first time it talks to each of
We will work out a time with you when your IP address can be migrated.
At that time, we will set your VM to migrate, and you will change the
configuration files for your daemons. Once the machine's IP address
-migrates, you will restart the daemons or turn your server off and then
-back on (note that a reboot will not result in a functioning network
-connection; the very first time that you restart your VM after its IP
-is migrated, you must do so by turning it completely off and then back on).
+migrates, you will restart the daemons or reboot your server.
## Should I contact you about my VM's renumbering? When do I need to contact you by?
contact us and we'll do our best to answer them. If your VM requires
special coordination (for example, due to any of the reasons listed in
the "Do I need to take any action?" question near the top of this page),
-you should definitely contact us no later than Sunday, June 3. If anything
+you should definitely contact us no later than Sunday, August 4. If anything
goes wrong during your VM's migration, again, we need to hear from you.
Finally, if you have feedback about the process that you would like to share,
we welcome you to contact us.
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