Re: [dc] 答复: Re: Requirement for a method to manage mac address in DC

Virtual Center [VMware management software] uses combination of one of the OUI assigned to VMware and Virtual Center ID [which can be configured] to generate MAC address with in a range for VM's use. It ensures that MAC address assigned to VMs that are managed by it gets non overlapping MAC address. 

Mallik 

----- Original Message -----

From: "yu jinghai" <yu.jinghai@zte.com.cn> 
To: "Mallik Mahalingam" <mallik@vmware.com> 
Cc: "Thomas Narten" <narten@us.ibm.com>, "Truman Boyes" <tboyes@gmail.com>, dc@ietf.org, "Lizhong Jin" <lizho.jin@gmail.com> 
Sent: Thursday, February 2, 2012 10:08:39 PM 
Subject: [dc] 答复: Re: Requirement for a method to manage mac address in DC 

Hi Mallik: 
I learned about that Xen generate MAC address by an algorithm base the timestamp. 
I don't know well about other virtualization platform. 
As you say that: 
> There is some notion of Management-Entity(s)/controller(s) allocating the 
> MAC addresses for VMs and ensures that it does not assign the same MAC 
> address to two different VMs and this work only within the scope of that 
> management/controller administration. 

why does it work only within the scope of that management/controller administration? 
How do VMs get the MAC addresses? 
Could you please elaborate? 

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Mallik Mahalingam <mallik@vmware.com> 写于 2012-02-03 03:21:56: 

> In a virtualized environment MAC addresses are not totally random generated. 
> There is some notion of Management-Entity(s)/controller(s) allocating the 
> MAC addresses for VMs and ensures that it does not assign the same MAC 
> address to two different VMs and this work only within the scope of that 
> management/controller administration. There are some exceptions of course 
> (a) MAC address exhaustion under a given OUI category (b) manual 
> copy/cloning of VMs and powering on them using standalone management 
> entities (c) VMs that use MAC address override for legitimate reasons 
> [because else things like licensing software breaks]. There are some 
> mechanisms in place to address (a), but (b) and (c) requires co-operation at 
> the management-entity/controllers. 
> 
> Mallik 
> 

> From: "Truman Boyes" <tboyes@gmail.com> 
> To: "Thomas Narten" <narten@us.ibm.com> 
> Cc: "yu jinghai" <yu.jinghai@zte.com.cn>, dc@ietf.org, "Lizhong Jin" 
> <lizho.jin@gmail.com> 
> Sent: Thursday, February 2, 2012 10:20:07 AM 
> Subject: Re: [dc] Requirement for a method to manage mac address in DC 
> 
> 

> On Thu, Feb 2, 2012 at 10:55 AM, Thomas Narten <narten@us.ibm.com> wrote: 
> Truman Boyes <tboyes@gmail.com> writes: 
> 
> > The L2 separation between multiple tenants is true in most circumstances in 
> > DCs, but in commodity computing (ie. VPS, low cost dedicated servers, or 
> > co-location) there is a concern on IPv4 address exhaustion or waste, so 
> > machines/instances are grouped on single L2 segments. It is possible to 
> > have virtual MAC overlaps on these segments. Is this something that this 
> > group wishes to evaluate options to solve? 

> IMO, this is putting the cart before the horse. 
> 
> Can we first get a sense for how big a problem this is in practice and 
> whether existing mitigation approaches are not sufficient? 
> 
> I.e., is this a real problem causing significant pain today, or are 
> their other bigger "pain points" that we should be looking at? 
> 
> Thomas 

> 
> In the VPS/VM world, I would say it's not a significant issue 
> because there are single entities (Organizations) that manage the 
> MAC addresses. Typically software would just increment the virtual 
> MACs, and this does not require external protocols to ensure 
> uniqueness. If there are many provisioning systems that manage VMs 
> on the same network segment then they will need to keep their 
> database in sync. 
> 
> -- 
> --truman 
> 
> 
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