[one-users] 转发: 回复: Re: what a virtual network means?

[shamaya]

2011-11-22



shamaya



发件人: "shamaya"<shamaya at 126.com>
发送时间: 2011-11-22 09:30
主 题: 回复: Re: [one-users] what a virtual network means?
收件人: "Hutson Betts"hut101 at tamu.edu



 I have a question and two advices for OpenNebula's network configuration

Question:
1. Can I use VLAN function on a "physical network" which already running VLAN on the phical swich? (you know, in Eucalyptus, VLAN cann't function properly in such a environment: "underlying physical network must be VLAN clean", http://open.eucalyptus.com/wiki/EucalyptusNetworkConfiguration_v2.0)


Document advices:
1. Maybe, User's life would be more easier if OpenNebula's document on network include a network configuration example to help user build their cloud on their data center, for both physical and logical network configuration. again, Eucalyptus have included such guides for users at http://open.eucalyptus.com/learn/InstallingECC

2. Mybe it is helpful to give a throughout network configuration process expample, e.g. you mentioned cloud builder need to setup a bridge on every work node, but I did found a example. 




Cheers,
Sha



2011-11-22



shamaya



发件人: Hutson Betts <hut101 at tamu.edu>
发送时间: 2011-11-21 12:14
主 题: Re: [one-users] what a virtual network means?
收件人: shamaya <shamaya at 126.com>



Dear Sha, 

Have you had an opportunity to read through Managing Virtual Networks 
3.0 (http://opennebula.org/documentation:rel3.0:vgg)? Honestly, I think 
it covers virtual networking better than any of the other OpenNebula 
configuration documents. 

However, I would look outside of OpenNebula for a truly in-depth 
analysis of virtual networking, VLANs, and cloud networks. 

But, to answer your question, a single virtual network is analogous to a 
physical switch containing a DHCP server. Virtual machines attached to 
this "physical" switch are isolated from network traffic on another 
"physically separated" switch, which in this case is another virtual 
network. 

Now, with regard to the DHCP server, OpenNebula allows virtual networks 
to lease IP addresses to virtual machines that attach to the network. 
Each IP address can only be leased, or owned, by one virtual machine on 
that virtual network at any one time. When a virtual machine starts, it 
is automatically assigned an IP address by OpenNebula. The trick is to 
know that the MAC address assigned to the virtual machine is a 
transformation of the IP address. 

Consider an example in the document linked earlier: 
A MAC address of: 00:03:c0:a8:00:01 
Corresponds to an IP address of: 192.168.0.1 
You can do the hex to int conversion: 
c0 = 192 
a8 = 168 

Now, from a computer perspective, there are quite a few ways to isolate 
the network traffic between virtual networks, i.e., vlans, ebtables for 
mac filtering, Open eSwitch. etc. This part you must consider carefully 
when you wish to expand beyond one virtual machine host, or when you 
want to use overlapping IP ranges for different virtual networks. 

From an administrator point, all that is required of you is to create a 
bridge, and attach it to a physical Ethernet (network) interface on your 
virtual machine host. 

Next, when creating new virtual networks using network templates, you 
can specify the name of that bridge. Also, if you decide to use OCCI, 
you can specify in the OCCI configuration file, the name of that bridge 
as well. 

As you've already hinted at, when virtual machines are created, their 
virtual network interfaces are attached to the bridge, either directly, 
or by another mechanism such as when using VLAN tagging. In either case, 
the bridge acts as the central "physical" switch for your virtual 
networks, passing traffic between virtual machines. 

Now, because the bridge is attached to your virtual machine host's 
physical network interface, your virtual machines will also be able to 
send traffic to virtual machines on other virtual machine hosts on the 
same physical switch, literally the physical switch this time. 

Please let me know if my explanations could use refinements, or if you 
have any further questions. Also feel free to write out a list of ideas 
you have for improving the documentation on OpenNebula. I'm sure the 
community would greatly appreciate any help you're able to provide. 

--  
Hutson Betts 
Computer Science and Engineering 
Texas A&M University 


On Mon, 2011-11-21 at 10:02 +0800, shamaya wrote: 
> Hi all, 
>    OpenNebula's document on network seems a bit incomplete, and I feel  It's difficult to understand what a virtual network means?  Does a vritual network means create a bridge on a host and connect all VMs of that host to it? Can a virutal network span two host and let VMs of the two form a private network? 
>  
> Regards. 
>  
> Sha 
>  
> 2011-11-21 
>  
>  
>  
> shamaya 
> _______________________________________________ Users mailing list Users at lists.opennebula.org http://lists.opennebula.org/listinfo.cgi/users-opennebula.org 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.opennebula.org/pipermail/users-opennebula.org/attachments/20111122/7d5e1b71/attachment-0002.htm>