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From "Imran Ahmed" <>
Subject RE: Auto Generating MAC Addresses for VMs in a given pattern
Date Thu, 11 May 2017 17:44:05 GMT
Hi Sergey,

I am grateful for your prompt reply. The data center provider has provided a starting sequence
to be used. Do you think it would be another option to modify the sequence in db tables (data_center
and user_ip_address) so that the VMs get an IP/MAC from that sequence? Is  the randomization
function called during creation of each VM  or its run just once during the creation of zone

Kind regards,


-----Original Message-----
From: Sergey Levitskiy [] 
Sent: Thursday, May 11, 2017 10:16 PM
Subject: Re: Auto Generating MAC Addresses for VMs in a given pattern

Mac address is dynamically created based on the IP address sequence number being allocated
on your subnet with randomization algorithm.
It is done in 

    public static long createSequenceBasedMacAddress(final long macAddress) {
        return macAddress | 0x060000000000l | (long)s_rand.nextInt(32768) << 25 &

Starting sequence of your address is defined in data_center table and carried over to user_ip_address
tablewhere it gets properly incremented.

Routers use slightly different pattern for mac addresses.

I would advise to figure out another way of addressing your issue vs modifying ACS code that
deals with MACs.


On 5/11/17, 9:27 AM, "Imran Ahmed" <> wrote:

    Dear Team,
    We are in a situation where the datacenter provider has put a restriction on
    the MAC addresses.
    We Cloudstack 4.3 with XenServers 6.5 .  We need to modify the pattern in
    which the guest VMs get the MAC address and use the pattern provided by the
    datacenter provider.
    Please suggest what should be a good starting point ?
    Best regards,

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