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zmitya
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VM host replacement

Tue Feb 07, 2023 11:31 pm

Dear All,

I am still a newbie to MT and I have limited network knowledge. I do have a Linux server which has a public IP and I have a /27 public network routed to that IP. The Linux server hosts several VMs where each VM owns one or more public IPs from that /27 network.

I would like to replace that Linux host with a new server. The plan is to put the new one next to the old one (temporarily), get a MikroTik front of them and I would copy over the VMs one by one, make sure that the service works. When I finished (will take a few days) I would remove the old server and the MT.

What I DO NOT want to do is NAT. I don't want to reconfigure all the VMs prior the move and then re-do the same again when I remove the MT and the old server. The aim would be to "move" the public IP from the old server one by one somehow.

One important note is that my ISP does not allow to do Proxy ARP !!!

Could you guys please help me out where to look, please give me some pointers / advices how can I achieve this (if it is possible).

Thank you,
Mitya
 
ConradPino
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Re: VM host replacement

Tue Feb 07, 2023 11:50 pm

Sounds feasible but the devil is always in the details. So far one Linux based virtualization host is in the picture with second on the way.
Nothing said about which MT and that matters much.
Nothing said about ISP interface, type, speed, etc.
No NAT and no Proxy ARP, suggest VLAN tricks.

One free IP address needed to manage MT; public IP is simplest; private IP requires proxy on old or new server.

IF your new host and old host have different IP address AND guest VM are down while copy in progress THEN any dumb switch will do; skip the VLAN tricks; no extra IP address needed.
Last edited by ConradPino on Wed Feb 08, 2023 12:10 am, edited 1 time in total.
 
zmitya
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Re: VM host replacement

Wed Feb 08, 2023 12:04 am

I bought the MT a year ago and currently it is not around, but I can check it tomorrow.
I believe this is it: https://mikrotik.com/product/rb4011igs_rm

The server is in a co-location center, so I do get the connection via ethernet cable, the bw is 1Gbit/sec.

Because it is a proper server ISP, I can get a public IP dedicated to MT, that is not a problem.
 
zmitya
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Re: VM host replacement

Wed Feb 08, 2023 12:14 am

IF your new host and old host have different IP address AND guest VM are down while copy in progress THEN any dumb switch will do; skip the VLAN tricks; no extra IP address needed.

So, could you please describe the process ?
What is in your head ?
 
ConradPino
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Re: VM host replacement

Wed Feb 08, 2023 12:22 am

A dumb switch is a single Layer 2 broadcast domain (bridge) where MAC Address must be unique IN THE TIME DOMAIN.
VM on old host goes down - MAC Address no longer in use.
VM on new host comes up - MAC Address in use again.
There is no MAC Address overlap in time.
VM presumed to have unique MAC.
 
zmitya
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Re: VM host replacement

Wed Feb 08, 2023 12:30 am

A dumb switch is a single Layer 2 broadcast domain (bridge) where MAC Address must be unique IN THE TIME DOMAIN.
VM on old host goes down - MAC Address no longer in use.
VM on new host comes up - MAC Address in use again.
There is no MAC Address overlap in time.
VM presumed to have unique MAC.
It can't be that simple :)
I might over-complicated it...
So it looks simpler than I thought... :)

I really appreciate it..
Let me think it over again .. :)
 
ConradPino
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Re: VM host replacement

Wed Feb 08, 2023 12:42 am

Dumb switch is similar to High Wire Act Without A Net. Measure that against your Personal Oops Index.

RB4011 will bridge which is good enough AND is can remap down VM guest IP address to maintenance page.
 
ToryRutter
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Re: VM host replacement

Wed Feb 08, 2023 8:04 am

Therefore, could you help explain the procedure.
What are you thinking?
Last edited by ToryRutter on Wed Feb 08, 2023 8:06 am, edited 1 time in total.

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