Vlan transition/ IP Changes

Posted on 2012-08-30
Last Modified: 2012-09-07
Hi all,

I'm meant be performing a task which involves 600 Virtual servers( Linux, Windows -  running on vSphere env with several esx hosts.)  to be re-IP'd which includes the VLan's where these servers run on.
So, I'm supposed to come up with a  high level design plan/document ( not doing the work myself)  overview of tasks to ensure that everything involved in doing a re-IP of a server which includes adding/moving to new Vlan's is thought about.
There will be appropriate SME's who will carry out the work, ie: System Admin's,
network people, ESX people, Database people, Storage people, Application people, etc,etc,etc.

So far I have the bottom "pieces", but I'm sure that I've
missed quite a few...

some of things I've come up with

- assume change mgmt processes will be used and coordinated
- assume that all apps are able to be re-IP'ed ( we don't know this )
- all apps shutdown with no restart before doing any work.
- all esx hosts are able to support/connect to the new Vlans
- the datastores have to be available to different vcenters that will
host VM's
- add into ipam new ipadresses
- dns reverse/forwarded - take into account it takes time to propagate
- re-ip actual servers
- put back old ip addresses/ Remove from IPAM
- re ip the actual applications
- Database Ip changes, ie: tnsnames.ora
- what apps have to be moved together, ie: group of machines, for
example, 3 tier app, should be moved together where possible.
- backups .. are there any existing "live" backups and if they need to
be restored, would it be able to be restored to new infrastructure, ie: new storage
- what sort of storage vmdk, san/netapp, emc, Iscsi on the vcenters.
Are there any firewalls between these and the new Vlan's/ESX
infrastructure ?
- Current mgmt servers/ automation/ monitoring. How will they know
about the "migrated"/ re IP'ed servers.
- When do the mgmt servers get migrated, first/last ?

Has anyone done such a task before and is able to contribute/assist in this matter?

thanks for taking the time to read this and to give their opinions and share their experience.

Question by:couta
    LVL 8

    Accepted Solution

    Has your new VLAN and IP address architecture been designed?  If so, how is it structured for both VLANs and IP addresses?  For example, I use a 10.SITE.VLAN.HOST addressing scheme and then VLANs are grouped into categories, which then the VLAN category are logically grouped by ACL wildcard masking (2, 4, 8, 16, 32); networks per VLAN category.

    You need to out line the steps and define all the dependencies.  Once the underlying network has been configured the system level changes are straight forward, but application may not be.  

    1. Plan and implement new VLANs and IP Addrssing scheme.
        a. Do current VLANs numbers overlap with new VLAN IDs?  If so, plan VLAN migration otherwise apply new configuration.

        b. Implement new IP addressing scheme throughout network infrastructure where applicable.  Make sure all networks can communicate between routers, switches, firewalls, and other network devices.  

        c. Plan and Implement new VLAN and IP addressing scheme to Core infrastructure systems including SAN/NAS, VMware vCenter and ESX, Active Directory, DNS, host files, DHCP, etc... (where applicable).  Complete all physical changes first then virtual machines.

    As far as, VMware ESX make sure your virtual switches are properly architected and migrated.  Then apply the new VLANs and IP addresses to the Virtual Machines starting with the least complicated systems first.  Applications may have Legacy IP addresses in .ini files, code (java, HTML, etc...), registry, and more...

    Part of the migration plan is to take a snapshot of the current system configuration, then transition, and finally completion.  When planning migrations sometime you may find it's not always straight-forward (current to completed).  In other words, the transionsl phase may need to be required.  Each system is different, so it's important that every step is planned.  For me, I will use Visio Diagrams and spreadsheets of each phase, which helps identify any challenges.

    Author Closing Comment


    thanks for your input. I'll take some of your comments as input to formulate the doc.


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