Hi Sergey,

Bundle of thanks for your valuable input on this. I will do some research and 
see what can be the best alternative for this.

Kind regards
Imran

-----Original Message-----
From: Sergey Levitskiy [mailto:[email protected]] 
Sent: Thursday, May 11, 2017 10:57 PM
To: [email protected]
Subject: Re: Auto Generating MAC Addresses for VMs in a given pattern

Randomization is done for each VM. The only static part is prefix - 06. Unless 
you change the ACS code it won’t support a predefined range for Mac addresses. 
If you sort you nics table by IP address you will see that octet on the rigtht 
gets incremented due to respective sequence increment. But at the same time 
second and third octet on the left change due to randomization.

On 5/11/17, 10:44 AM, "Imran Ahmed" <[email protected]> wrote:

    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 
(data_center)?
    
    Kind regards,
    
    Imran 
    
    -----Original Message-----
    From: Sergey Levitskiy [mailto:[email protected]] 
    Sent: Thursday, May 11, 2017 10:16 PM
    To: [email protected]
    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 NetUtils.java 
    
        public static long createSequenceBasedMacAddress(final long macAddress) 
{
            return macAddress | 0x060000000000l | (long)s_rand.nextInt(32768) 
<< 25 & 0x00fffe000000l;
        }
    
    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.
    
    Thanks,
    Sergey
    
    
    
    
    On 5/11/17, 9:27 AM, "Imran Ahmed" <[email protected]> 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,
        
        Imran 
        
        
    
    
    


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